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**collector240sx** · 11-14-2009, 08:06 PM

Chapter One - Motor Oil 101

I think it is time to go over passenger car automotive engine oils in detail. I
will be writing several articles to be published soon so I will try to get some
of it out here. I feel this is a very general topic for all car owners on this
board.

This is a very difficult topic to comprehend. Everybody including good
mechanics think they are experts in this field but few understand engine oils.
Most of what I hear is the opposite of the truth. It is however easy to see
how people get mixed up as there is always some truth to the misconception.

Please forgive me if I am too wordy or even verbose at times. I will be
redundant for certain. This will be in areas that people have to hear things
over and over again to get it right. Some will never be able to understand
these concepts unfortunately. I base my thoughts on those whom I have
been listening to in various automotive chat rooms and discussion with
mechanics. I will try to minimize technical terms and be somewhat vague
rather than exact. I will round and average numbers to make the point simple
rather than mathematically exact. Thickness has the same meaning as
viscosity. Viscosity is a measure of the resistance of a fluid (liquid or gas) to
flow. Fluids with high viscosity, such as molasses, flow more slowly than
those with low viscosity, such as water. Again, I am trying to explain general
principals as I know them.

The greatest confusion is because of the way motor oils are labeled. It is an
old system and is confusing to many people. I know the person is confused
when they say that a 0W-30 oil is too thin for their engine because the old
manual says to use 10W-30. This is wrong.

More confusion occurs because people think in terms of the oil thinning when
it gets hot. They think this thinning with heat is the problem with motor oil. It
would be more correct to think that oil thickens when it cools to room
temperature and THIS is the problem. In fact this is the problem. It is said
that 90 percent of engine wear occurs at startup. If we are interested in
engine longevity then we should concentrate our attention at reducing
engine wear at startup.

Oils are chosen by the manufacturer to give the right thickness at the normal
operating temperature of the engine. I will say this average oil temperature is
212 F, the boiling point of water. On the track that temperature is up to 302
F. It is important to realize that these are two different operating
environments and require different oils.

I will discuss driving around town first. Everything I say will be based on
these conditions. At a later time I will discuss track conditions. Everything I
say will be as accurate as possible without looking everything up and
footnoting. I am trying to be general not ultra specific.

One thing that is no longer important is the ambient temperature. Older
automotive owner manuals often recommended one oil for the summer and
another for the winter. This is still necessary for air cooled engines but is no
longer a consideration in pressurized water cooled engines. These engine
blocks are kept at around 212 F all year round. The oil is around the same
temperature as well. This allows for a single weight oil all year round. Again,
this is not the same as on the track where the coolant temperature is slightly
higher and the oil temperature is much higher.

Please forget those numbers on the oil can. They really should be letters as
AW-M, BW-N or CW-P. The fact that we are dealing with a system of
numbers on the can makes people think that they represent the viscosity of
the oil inside the can. The problem is that the viscosity of oil varies with its
temperature. A �30� weight oil has a viscosity of 3 at 302 F ( 150 C ) and
thickens to 10 at 212 F ( 100 C ). It further thickens to a viscosity of 100 at
104 F ( 40 C ) and is too thick to measure at the freezing point of 32 F ( 0 C ).

30 weight oil:

Temperature ( F )....Thickness

302...........................3
212..........................10
104..........................100
32..........................250 (rough estimate)

The automotive designers usually call for their engines to run at 212 F oil and
water temperature with an oil thickness of 10. This is the viscosity of the oil,
not the weight as labeled on the oil can. I want to stay away from those
numbers as they are confusing. We are talking about oil thickness, not oil can
labeling. This will be discussed later. Forget the numbers on that oil can for
now. We are only discussing the thickness of the oil that the engine requires
during normal operating conditions.

The engine is designed to run at 212 F at all external temperatures from
Alaska to Florida. You can get in your car in Florida in September and drive
zig-zag to Alaska arriving in November. The best thing for your engine would
be that it was never turned off, you simply kept driving day and night. The oil
thickness would be uniform, it would always be 10. In a perfect world the oil
thickness would be 10 at all times and all temperatures.

If the thickness of oil was 10 when you got in your car in the morning and 10
while driving it would be perfect. You would not have to warm up your
engine. You could just get in the car and step on the gas. There would be
little wear and tear on you engine, almost none. Unfortunately the world is
not perfect.

The night before when you drove home from work the car was up the the
correct operating temperature and the oil was the correct thickness, 10.
Over night the engine cooled to room temperature and the oil thickened. It is
75 F in the morning now (I do live in Florida). The oil thickness is now around
150. It is too thick to lubricate an engine designed to run with an oil having a
thickness of 10.

It is time to introduce the concept of lubrication. Most believe that pressure
= lubrication. This is false. Flow = lubrication. If pressure was the thing that
somehow lubricated your engine then we would all be using 90 weight oil.
Lubrication is used to separate moving parts, to keep them from touching.
There is a one to one relationship between flow and separation. If you double
the flow you will double the separation pressure in a bearing. The pressure at
the bearing entrance is irrelevant.

In fact the relationship between pressure and flow is in opposition. If you
change your oil to a thicker formula the pressure will go up. It goes up
because the resistance to flow is greater and in fact the flow must go down
in order for the pressure to go up. They are inversely related. Conversely if
you choose a thinner oil then the pressure will go down. This can only occur
if the flow has increased.

It seems then that we should all be using the thinnest oil money can buy.
This is partly true. Let me use my 575 Ferrari Maranello as an example. I drive
this car around town. The manual of this car states the target pressure is 75
PSI at 6,000 RPM. The gold standard is that all engines should have a
pressure of 10 PSI for every 1,000 RPM of operation, not more, not less.
After all, you do need some pressure to move that oil along, but only enough
pressure, not more. More pressure is not better, it can only result from the
impedance of oil flow. Remember that oil flow is the only thing that does the
lubricating.

Note that Ferrari is not saying what thickness of oil to use. That can only be
determined by experimentation. My engine oil temperature is running around
185 F as I drive around town on a hot Florida summer day. I have found that
the thinnest oil I can buy that is API / SAE certified is Mobil 1�s thinnest oil.
Even with this oil I get 80 PSI at 2,000 RPM. It is too thick for my application
yet it is the thinnest oil money can buy. If I was on a hot Florida track in mid-
summer the oil temperature would probably get up to 302 F. I will guess that
the pressure would only be 40 PSI at 6,000 RPM. The oil I am using would not
meet the requirement of 75 PSI at 6,000 RPM from Ferrari. I would have to
choose a thicker oil for this racing situation. The oil I use now would be too
thin at that very high temperature. (This is only partly true. Higher RPM
running engines use thinner and thinner oils to get more and more flow. I will
discuss this later).

High flow does more than lubricate. It is one of the things used to cool the
hottest parts of your engine, the pistons, valve areas and bearings. This
cooling effect is as important as lubrication in your engine. If your engine is
running hot use a thinner oil. The flow will increase and so will the cooling.
This is even more important in the racing condition.

Let us go back to the Ferrari manual. My older 550 Maranello only specified 5
W-40 Shell Helix Ultra as the oil to use in all conditions. This car was
designed for racing. As it turns out Ferrari now recognizes that not every
owner races their cars. The newer 575 manual now states to use 0W-40 for
around town situations even though Shell does not make this oil in the Helix
Ultra formulation at this writing. They also recommend the 5W-40 by Shell if
you insist on the Shell product. It is also the recommended oil for most racing
conditions.

**collector240sx** · 11-14-2009, 08:07 PM

Ferrari recommends Helix Ultra Racing 10W-60 “for hot climate conditions
racing type driving on tracks”. Note that they now realize the difference
between the daily urban driver like me and the very different racing situation.
These are widely different circumstances. I want to emphasize that they only
want you to use this oil while racing in “hot climate conditions”. If you are
racing in Watkins Glen up north use the 5W-40. If you are racing in Sebring in
the middle of the Florida summer use the 10W-60. Around town in any
climate, use the 0W-40.

It is time to dispel the notion that 0W-30 oil is too thin when our manual calls
for 10W-30. A 0W-30 is always the better choice, always. The 0W-30 is not
thinner. It is the same thickness as the 10W-30 at operating temperatures.
The difference is when you turn your engine off for the night. Both oils
thicken over the evening and night. They both had a thickness, a viscosity of
10 when you got home and turned your engine off. That was the perfect
thickness for engine operation.

As cooling occurs and you wake up ready to go back to work the next day
the oils have gotten too thick for your engine to lubricate properly. It is 75 F
outside this morning. One oil thickened to a viscosity of say 90. The other
thickened to a viscosity of 40. Both are too thick in the morning at startup.
But 40 is better than 90. Your engine wants the oil to have a thickness of 10
to work properly. You are better off starting with the viscosity of 40 than the
honey - like oil with a viscosity of 90.

I repeat: More confusion occurs because people think in terms of the oil
thinning when it gets hot. They think this thinning with heat is the problem
with motor oil. It would be more correct to think that oil thickens when it
cools to room temperature and THIS is the problem. In fact this is the
problem.

This is the end of lesson number one.

**collector240sx** · 11-14-2009, 08:10 PM

Motor Oil 102
Chapter two. It gets more difficult.

We left off discussing that a 0W-30 weight oil is not thinner than a 10W-30
oil. They both have the same thickness at operating temperature. The 0W-30
simply does not get as thick on cooling as the 10W-30. Both are still way to
thick to lubricate an engine at startup.

I have heard several people say that Porsche specifically prohibits a 0W-XX
engine oil, that it is too thin. Now here is the partial truth I spoke of earlier.
We will discuss multigrade oils. Earlier we said that a straight 30 weight oil
has a thickness of 10 at the normal operating temperature of your engine.
The multigrade oils 0W-30 and 10W-30 also have a thickness of 10 at 212 F.

The difference is at 75 F, your startup temperature in the morning.

Oil type... Thickness at 75 F...Thickness at 212 F

Straight 30...... 250......................10
10W-30............100......................10
0W-30..............40 ......................10

Straight 10........30....................... 6

Now you can see that the difference between the desired thickness your
engine requires ( = 10 ) is closest to the 0W-30 oil at startup. It is still too
thick for normal operation. But it does not have far to go before it warms up
and thins to the correct viscosity. Remember that most engine wear occurs
at startup when the oil is too thick to lubricate properly. It cannot flow and
therefore cannot lubricate. Most of the thick oil at startup actually goes
through the bypass valve back to the engine oil sump and not into your
engine oil ways. This is especially true when you really step on that gas
pedal. You really need more lubrication and you actually get less.

Note that a straight 10 weight oil is also too thick for your engine at startup.
It has a thickness of 30. Yet at operating temperatures it is too thin having a
thickness of 6. It needs to be around 10. The oil companies have added
viscosity index improvers or VI to oils to solve this dilemma. They take a
mineral based oil and add VI improvers so that it does not thin as as much
when it gets hotter. Now instead of only having a thickness of 6 when hot it
has a thickness of 10, just as we need.

The penalty is the startup thickness also goes up to 100. This is better than
being up at 250 as a straight 30 weight oil though. Oil with a startup
thickness of 100 that becomes the appropriate thickness of 10 when fully
warmed up is called a 10W-30 weight motor oil. This is NOT as thick as a
straight 30 weight oil at startup and it is NOT as thin as a straight 10 weight
oil at full operating temperature.

The downside of a mineral based multigrade oil is that this VI additive wears
out over time and you end up with the original straight 10 weight oil. It will
go back to being too thin when hot. It will have a thickness of 6 instead of 10
. This may be why Porsche (according to some people) does not want a 0W-
30 but rather a 10W-30. If the VI wears out the 0W-30 will ultimately be
thinner, a straight 0 weight oil. When the VI is used up in the 10W-30 oil it
too is thinner. It goes back to a straight 10 weight oil. They are both still too
thick at startup, both of them. The straight 0 weight oil, a 5 weight oil and a
10 weight oil are all too thick at startup.

This is just theory however. With normal oil change intervals the VI improver
will not wear out and so the problem does not really exist. In fact, oils do
thin a little with use. This is partly from dilution with blow by gasoline and
partly from VI improvers being used up. What is more interesting is that with
further use motor oils actually thicken and this is much worse than the
minimal thinning that may have occurred earlier.

Synthetic oils are a whole different story. There is no VI improver added so
there is nothing to wear out. The actual oil molecules never wear out. You
could almost use the same oil forever. The problem is that there are other
additives and they do get used up. I suppose if there was a good way to
keep oil clean you could just add a can of additives every 6 months and just
change the filter, never changing the oil.

When the additives wear out in a synthetic oil it still has the same viscosity.
It will not thin as a mineral oil. The fear that some say Porsche has that oils
thin when the VI runs out is not applicable to these synthetic oils. These oils
will always have the correct thickness when hot and will still be too thick at
startup as with all oils of all types, regardless of the API / SAE viscosity
rating.

Automotive engine manufacturers know these principals of motor oils. They
know there is thinning or thickening that will occur. They take these things
into account when they write that owners manual. Mineral oil change
recommendations will generally include shorter time intervals than those of
synthetic oils.

The reality is that motor oils do not need to be changed because they thin
with use. It is the eventual thickening that limits the time you may keep oil in
your engine. The limit is both time itself (with no motor use) and/or mileage
use.

End of part two.

**collector240sx** · 11-14-2009, 08:12 PM

Motor Oil 103
Part Three. You have a synthetic mind.

Let us compare mineral and synthetic oils. I will not talk about chemical but
rather functional differences. We discussed before how mineral oils are too
thick at startup yet too thin when hot. The viscosity was corrected with the
hot engine by adding VI improvers.

A 10W-30 multigrade mineral based oil is made from a 10 weight oil and has
VI improvers added to thicken the product in a 212 F engine. It acts as a 30
weight oil when hot. It acts more as a 10 weight oil at startup. I remind you
that a 10 or 5 or 2 weight oil is still too thick to provide lubrication at
startup. They are all too thick at startup. There is currently no engine oil thin
enough to operate correctly at startup. They all cause excessive wear at
startup. Again, we are discussing the needs of my single hypothetical engine
for around town driving.

Oil type.. Thickness at 75 F ..Thickness at 212 F

Straight 30..........250....................10
10W-30...............100....................10
0W-30.................40.....................10

Straight 10..........30.....................6
Straight 5...........20.....................4
Straight 2...........15.....................3
Straight 0...........12.....................3 est.

A 10W-30 synthetic oil is based on a 30 weight oil. This is unlike the
counterpart mineral oil based on a 10 weight oil. There is no VI improver
needed. The oil is already correct for the normal operating temperature of 212
F. It has a thickness of 10 while you drive to work. It will never thin yet has
the same long term problem as the mineral based oil. They both thicken with
extended age.

Synthetic oils are derived in the laboratory. They are pure, usually nearly
clear. I describe mineral based motor oils as a distilled, concentrated product.
The impurities need to be removed from the raw petroleum. These oils are
therefore less clean and contain many impurities. Again, the problem is really
more of theory than practice but the difference does exist.

People repeatedly say that synthetic oils are more stable in a hot engine. I
hear that they lubricate better. The answer is yes and no. Oil molecules do
not break down, just the additives. Generally, the synthetic oils do not have
VI improvers so have less to lose.

There are some properties of synthetic oils that actually result is less wear
than with mineral oils. These help increase your gas mileage as well. Due to a
reduction of internal friction of the synthetic oil your engine will run a bit
cooler. Wear increases as temperature increases, all other things being
constant.

A main advantage that the synthetic has over the mineral based oil is the
ability to lubricate at startup. Both types of oil have the same specifications
at 104 F, 212 F and 302 F. It is the startup viscosity characteristics that
separate these oils. Synthetic oils do not thicken as much on cooling. They
have better fluidity as the temperature drops.

A synthetic oil that is labeled as 10W-30 is less honey like as a mineral based
10W-30 motor oil at startup. They both have a thickness of 10 at normal
operating temperatures. At 75 F the synthetic is not as thick. At 32 F the
difference between the two is even greater. At 0 F the mineral oil is useless
yet the synthetic works fairly well. Just keep the RPM to a minimum.

At temperatures below zero you will not be able to start your car with mineral
oils while the synthetic oils may be used to -40 or - 50 F. Oils are so thick
that the normal method of viscosity measurement is not possible. Instead we
measure if the oil can even be pumped or poured. Again, we are only
discussing a single category of oil, the multigrade 10W-30 API / SAE grade.

I took an except from the web about Mobil 1 oils. They compared a 5W-30
synthetic Mobil 1 oil to a mineral based 10W-30 and a 10W-40 in ice cold
conditions. The engine turned over at 152 RPM with the synthetic 5W-30
Mobil 1. The 10W-30 and 10W-40 mineral oils turned over at 45 and 32 RPM
respectively. Neither of those engines started.

Motor oil becomes permanently thicker with exposure to northerly winter type
weather. This is more of a problem to mineral based oils. Waxes form. This is
why it is a bad idea to even store a bottle of oil in a cold garage. It goes bad
on the garage self just because it is exposed to the cold.

To recap, synthetic oils have similar characteristics as mineral oils at
operating temperatures. The synthetic oil will however be less honey - like at
startup even though it has the same API / SAE rating. Yet the synthetic 10
W-30 weight oil is based on a heavier 30 weight oil while the mineral based 10
W-30 oil is based on a thinner 10 weight oil. They are both similar at
operating temperatures yet the 30 weight based synthetic is actually less
thick at startup and much less honey - like at low temperatures. This is the
opposite of what common sense dictates.

This is worth repeating: The synthetic 10W-30 weight oil is based on a
heavier 30 weight oil while the mineral based 10W-30 oil is based on a thinner
10 weight oil. They are both similar at operating temperatures yet the 30
weight based synthetic is actually less thick at startup and much less honey -
like at low temperatures. This is the opposite of what common sense
dictates.

As one can see this is no easy topic. Are you with me?

**collector240sx** · 11-14-2009, 08:16 PM

Motor Oil 104
Part Four. It is not what we thought.

Now let us finish talking about the differences of mineral verses synthetic
oils. I will compare the same weigh or grade of oils showing that the
operating viscosities are the same whereas the startup viscosities vary:

Mineral oil:

Oil type...Thickness at 75 F... at 212 F...at 302 F

Straight 30..........250....................10..........3
10W-30...............100....................10........ ..3
0W-30..........There are none in this range......

Synthetic oil:

Oil type...Thickness at 75 F... at 212 F...at 302 F

Straight 30...........100...................10...........3
10W-30.................75...................10........ ...3
0W-30...................40...................10...... .....3

Since the synthetic oil thickens less on shutdown your startup will be easier
and so will the stress on your engine. This is perhaps the best thing the
synthetic class has over the mineral based oils.

People sometimes use a thicker oil to minimize gasket leaks. This seems
obvious to me. Repair the gasket. Do not destroy your engine with an oil that
is too thick for proper function.

Some people have said they use thicker oils because they only use their cars
every 2, 3 or 4 weeks. They are afraid that thin oils will fall off the engine
parts and result in a lack of lubrication at startup. Think about your lawn
mower over the winter. I gets gummed up solid. The oil and fuel thicken over
time resulting in engine failure. Anyway, oil on the surface of parts does not
lubricate. It is the FLOW of oil between parts that lubricates. Thick, old,
waxy oil can only be bad.

I have seen several car owner manuals that are now stating that oils do not
need to be changed but every 7,500 miles or more. The same manual also
states OR every 12 months, whichever occurs first. My feeling is that you
can probably go 5,000 miles on the average (in a sports car) but you must
change your oil in the spring time at a minimum, particularly up north. Oils
form waxes in icy cold weather. There is a permanent thickening of the oil.

Some automotive manufacturers are backing down on oil change intervals to
5,000 miles or less and some advocate changing the oil at least every 6
months as well. I think this is because of the tendency for oils to thicken in
very hot engines (not ambient conditions, just hot engines). Also because of
thickening from the cold of winter and from sludge build up that cannot be
filtered out.

I truly believe that oil is much better being too thin than too thick. Over the
years we have been going to thinner and thinner oils despite hotter engines
with turbos and the like. The tendency is that people figure they need a 40
weight oils but then use a 50 instead. Better thinking is that if you think you
need a 40, use a 30 weight oil instead. I firmly believe this based on all I
know about oils.

As it turns out synthetic oils do cling to parts better as they have higher film
strength than mineral oils. Synthetics are thinner overall. They have greater
slipperiness. Yet they stick better to engine parts. Again, this concept is the
opposite of normal thinking.

The thickness of moving oil is measured in centiStokes or cS. Most engines
want the oil viscosity to be around 10 cS at normal operating temperature.
The really thick multigrade oils have a viscosity of 20 cS at operating
temperature. One is not twice as thick as the other, it is only 10 cS thicker.

As we increase the heat from 212 F to 302 F the most commonly
recommended oil thins from 10 cS to 3 cS. The thicker oil drops from 20 cS
to 4 cS. Note that in a very hot engine the difference between the two oils
is now only 1 - 2 cS. In other words they have about the same thickness.
There is little advantage to a thicker based oil as a 20W-50 at very high
temperatures. No, the 4 cS oil is not twice as thick as the 2 or 3 cS oil. This
difference is almost insignificant.

There is a huge advantage of using the thinner, 10W-30 at startup where 90
percent of the engine wear occurs. At 75 F the thicker oil has a viscosity in
the range of 250 cS while the thinner oil has a viscosity of 100 cS. The
thicker stuff is 150 cS thicker. This is a very big difference. I am using the 20
W-50 as my thicker oil example here.

People are always asking about adding things as Slick 50 into the oil tank. Do
not do this. The oil companies and engine manufacturers work together very
hard to give you the product you need. Engines are running hotter, longer
with more BHP from less CID. Smaller, more efficient engines are getting us
more MPG and yet better acceleration. These engines last longer and are
more reliable.

Part of that reason is the nature of the lubricants. There is a lot of
competition to get us the best working motor oil. Independent additives
cannot make the oil better and in many cases makes things worse. There
have been engine failures as a result of adding some of these aftermarket
additives to motor oil.

Motor oil that is labeled for RACING ONLY is not usable for every day driving.
Often these have more additives that are toxic to your catalytic converters
and the environment. These oils generally do not have detergents. These are
very important for your engine unless you plan on taking it apart every few
weeks and cleaning every single surface. The oils do not meet the API / SAE
requirements for ratings as SJ, SL or now SM.

You do not need to use the exact oil type and brand that your car manual
tells you to use. Oils are pretty general. They are not that different. Ferrari is
married to Shell. If you call them up and ask to use Valvoline instead they will
tell you that they have not tested that brand in their cars. They only tested
the engine with Shell oils. They cannot comment on the performance of other
oils in their engines. This is a fair statement. The reality is that the Shell and
Valvoline oils of the same specification (viscosity, API and SAE ratings,
synthetic or not) are very similar. ( I do have my bullet proof vest on ).

People often say that their old 1980 car manual says to use a specific Brand-
X motor oil. They keep trying to locate these older oils. First, just about any
oil brand that meets the original specifications will do. Second, all oils are
much, much better now. They are all much better. One could say that
synthetic oils are better than mineral oils but is is hard to say that one brand
is that much better than any other. Personally, I do stick to the big names.
It does not mean that small motor oil companies are not as good. They could
be better for all I know.

Using an oil that is less thick at startup has other benefits. Let us compare a
synthetic 10W-30 to a mineral based 10W-30. Both give you a viscosity of 10
cS at normal engine operating temperatures. They both thin to 3 cS at high
temperatures. At 75 F tomorrow morning the story will be different. The
startup viscosity of the synthetic will be 50 whereas the mineral based 10W-
30 will be 75. Again, both are too thick at startup but the synthetic will
cause less startup time period wear and tear. You will get a little better gas
mileage too.

The synthetic lubricated engine will turn over easier. This has the effect of
using less power from your starter motor. It will last longer. Your battery has
less of a current draw. This will also last longer. The battery was discharged
less during the start so the alternator will rob less power from your engine to
recharge. The alternator lasts longer and you get a little better gas
economy. The only downside of synthetic lubricants is the cost. They cost 2
or 3 times as much as mineral based oils. Never-the-less I use plain Pennzoil
multigrade mineral based 5W-20 in my Ford Expedition. This oil is thin enough
at startup to have many of the attributes I just mentioned.

**collector240sx** · 11-14-2009, 08:18 PM

Motor Oil 105
Part Five. Let�s use top gear:

Let�s go racing. I will discuss driving in traffic jams in the Florida summer as
well as racing in Sebring though there is no commonality. People lump these
two driving situations together but there is no overlap.

On the race track one usually uses all the BHP their engine can give them.
You briefly step on the brakes for the corner then put the pedal to the metal
the rest of the time. Your oil will get up to 302 F, but your cooling system is
around 212 F. The engine produces tremendous heat but can only pass it off
so fast to the cooling system. There is a lot of air moving past the cooling
radiator so the antifreeze / coolant is able to get rid of the extra heat from
this part of the system with relative ease.

The temperature of oil on your gauge is not as hot as it really gets. This
temperature is an average with oil from different parts of the motor. Some
parts are hotter than others. It is said that some of the oil gets as hot as 400
or 500 F in these racing situations.

In an earlier section I said that thicker oils are usually needed in racing
situations but not necessarily. Remember that a major function of oil is to
cool the inside of your engine. In ASTM D 4485 3.1.4: �Terminology: Engine
oil- a liquid that reduces friction and wear between moving parts within an
engine, and also serves as a coolant.� Since the oil with a viscosity of 10 cS
at 212 F thins to a viscosity of 3 cS at 302 F we will get more flow. The
pressure will go down some as well. This is OK as long as we have a minimum
of pressure to move the oil.

This increased flow will result in increased cooling by the oil. This is a good
thing. You would probably want more oil flow in these situations and you get
it. The hotter oil thins and this increases flow. The higher flow works harder
to separate the engine parts that are under very high stress. It all works out
for the better. Higher revving engines need thinner oils. You do not
necessarily need to go to a thicker oil while racing. Only experimentation will
tell.

The best way to figure out what viscosity of oil you need is to drive the car
in the conditions you will use. Then use the oil viscosity that gives you 10
PSI per 1,000 RPM under those circumstances. For some reason very few
people are able to get this simple principal correct. I cannot explain further.

These same rules apply to engines of any age, loose or tight. Just because
your engine is old does not mean it needs a thicker oil. It will need a thicker
oil only if it is overly worn, whether new or old. Yet the same principals of 10
PSI per 1,000 RPM still apply. In all cases you need to try different weight
oils and see what happens. Then choose the correct viscosity.

I am using 0W-20 in my Ferrari 575 Maranello right now. It has over 5,000
miles on the clock. There will be a day (my estimate is 50,000 miles) when I
will have to go to a 0W-30. In the future I will have to increase the viscosity
to a 0W-40, then a 0W-50, maybe. I will use whatever it takes to give me 75
PSI at 6,000 RPM during the lifetime of my engine. This formula works in all
situations.

Some people have tried this and occasionally get a somewhat low oil pressure
while at idle. This is fine. There is no stress on parts at idle, the smallest oil
flow will do the trick. It is at higher RPM where more BHP is produced. This is
where we need the flow. Remember that Ferrari uses 75 PSI at 6,000 RPM as
the place to test your oil viscosity needs. If your oil gives this value under
your driving conditions then your lubrication system has been maximized.
Period.

Do not go 5,000 miles with the same oil if you are racing your car. You should
change the oil every 1 or 2,000 miles. If you drive your car around town then
you need to change the oil for that situation. Use racing oil on the track and
urban oil around town. The best situation as described by Ferrari is to use
the 0W-40 around town and the 10W-60 �racing oil� on the track. It has to
be that �hot� track though. A compromise situation would be to use the 5W-
40 for both but this may not be optimal. Certainly, if you are just an urban
driver as me use the 0W-40 or even a thinner oil as I do in my Maranello.
Again, I use the 0W-20.

FYI. The Formula 1 cars that run at 15,000 RPM and higher use straight 5
and 10 weight oils.

Now let me discuss what people think is a similar situation to racing. That is
hot summer traffic jam driving. Your car should be able to handle this. If you
have problems then you have a problem with your car, most likely in need of
a cooling system overhaul.

When you drive that car down the road mid-winter in upstate New York or
mid-summer in Florida the engine and oil temperatures will be around 212 F.
But your Florida vacation is suddenly altered by a hurricane. You have to get
out of Tampa, but so do a million other people. It is now 95 F and you are in
a snarl. Everyone thinks they need a thicker oil for this situation. This is false.

Your engine is not producing much heat at low RPM and low BHP output. The
production of heat is relatively slow. It can easily be transmitted to your
cooling system. The problem is that your cooling system has trouble getting
rid of the heat. The oil and the coolant will slowly rise in temperature. They
both rise together. The increase is no big deal for your oil. It goes to 220,
then 230 F. The problem is that the cooling system can only handle heat up
to 230 F. After that you overheat the cooling system and the car must be
shut off. The oil never got that hot, It was just that the water got a little
hotter than its system design.

You now see that overheating in traffic is a cooling system problem and not
an oil system problem. Do not change to a thicker oil based on your traffic
situation.

**collector240sx** · 11-14-2009, 08:20 PM

Motor Oil 106
Part Six. A personal recommendation. (Updated in 2007)

These are the motor oils I recommend. This is based on information that I
just happened to collect. I have not gotten the specifications of all oils out
there. My opinion on these oils is based on viscosities. By this I mean less
honey like at start up temperatures and appropriate for the required viscosity
at operating temperature. I broke it down to several classes, 1-Fully
Synthetic, 1.2-Race Track, 2-Semi-Synthetic, 3-Mineral (dinosaur) oils. The
asterisk is my preferred from each group of very similar products. And these
are usually easier to find in my experience. Remember, all oils are too thick at
start up. There is no such thing as an oil that is too thin below 100 F. The
thinnest motor oil made is still too thick at start up temperatures.

It seems that many engines work best with a multigrade 30 weight oil. Others
would do better with a 20 weight oil and few would require a 40 weight oil.
You can only determine what is best by experimenting. Admittedly I did not
think my Ferrari Maranello would need a 20 weight oil. In truth I could
actually use a 10 weight oil. A 0W-10 would be good but it simply does not
exist for normal use. Red Line does make 2W, 5W and 10W oils (this acts as a
0W-10 multigrade oil) but they are for racing only. One Formula 1 team has
actually used these very oils off the shelf from Red Line.

�..Synthetic Class�..

60 wt:
Agip Synthetic PC 20W-50 (a thick 50 wt oil)
Redline straight 60 wt racing oil (racing only, acts as a SAE 20W-60 oil)*
Shell Helix Ultra Racing Oil 10W-60

50 wt:
Castrol Syntec 5W-50
Penn Synthetic 5W-50
Red Line 15W-50*
Shell Helix Ultra 15W-50

40 wt:
Amsoil 0W-40
Castrol European Formula 0W-30 (a thicker 30 wt oil, almost a 40 wt oil)*
Mobil One 0W-40

30 wt:
Mobil One 0W-30
Penn Synthetic 5W-30
Red Line 5W-20 (a thick 20 wt oil)*

20 wt:
Mobil One 5W-20*
Valvoline SynPower 5W-20

�..Race Oils for Street Use�..
Use these when continued sump temperatures over 240 F are expected.

60 wt:
Redline straight 60 wt racing oil (racing only, not for the street, acts as a
SAE 20W-60 oil)
Shell Helix Ultra Racing Oil 10W-60
Valvoline SynPower 20W-50

50 wt:
Castrol Syntec 5W-50
Shell Helix Ultra 15W-50

40 wt:
Red Line 5W-40
Shell Helix Ultra 5W-40

30 wt:
Red Line 10W-30

20 wt:
Amsoil 5W-20
Red Line 5W-20

�..Synthetic Blends�..

60 wt:
Castrol Syntec Blend 20W-50

50 wt:
Valvoline 20W-50

40 wt:
Agip 4-Synt 10W-40
Valvoline Durablend 10W-40*

30 wt:
Castrol Syntec Blend 5W-30
Motorcraft Blend 5W-30
Valvoline Durablend 5W-30*

20 wt:
Motorcraft 5W-20*
Valvoline Durablend 5W-20

�..Non-Synthetic�..

50 wt:
None recommended - all relatively too thick at start up.

40 wt:
Penn regular Multigrade 10W-40*
Valvoline All Climate 10W-40

30 wt:
Penn regular Multigrade 5W-30*
Valvoline All Climate 5W-30

20 wt:
Penn regular Multigrade 5W-20
Mobil Clean 5000 5W-20*

If while on the road you are forced to add oil there are rules. Let us say for
example that our engine has synthetic Mobil One 0W-30. Use the same type
and brand if you can. If you are using Mobil 1 then it is acceptable to mix
different grades but use a close grade when possible. It is not a good idea to
mix say 1/2 your oil tank with 0W-30 and 1/2 with 15W-50 Mobil 1. If there is
no Mobil 1 available then use the mineral based Mobil oils next,.

The last choice is to mix a synthetic of another brand. They should not react
adversely if mixed but it may dilute additives. This is not a good combination.
Use this combination if you must but only until an oil change can safely be
performed some time soon.

I personally used 0W-20 Mobil 1 in the 575 Maranello and for the first oil
change I drained the Murcielago�s (OEM) 5W-40 Agip and replaced it with 0W-
30 Mobil 1. The engine became much quieter. A valve tappet noise
disappeared. I am now using the 5W-20 Red Line in the Lamborghini. Used oil
analysis shows that this oil works well for my non racetrack application. The
same oil went into my Maybach 57. My Enzo Ferrari calls for the Shell Helix
Ultra racing 10W-60 but I am using the Castrol Syntec European Formula 0W-
30. This is different than the easy to find plain 0W-30 Syntec. It MUST say
European Formula across the front of the label. I buy it at AutoZone stores
but it is often mixed with the plain stuff.

You have to try by experimentation what operating oil grade your engine
requires. In all cases however, you want the oil that gets least honey-like at
startup and thins to the appropriate thickness for normal operation. Always
recheck the oil label as they change a lot.

**collector240sx** · 11-14-2009, 08:23 PM

Motor oil 107
Chapter Seven. What is the terminology from SAE and API.

Many think that the �W� in 10W-30 means �winter�.
From SAE J300 p.2:
"Two series of viscosity grades are defined in Table (1): (a) those containing
the letter W and (b) those without. Single viscosity grade oils with the letter
W are defined by maximum low temperature cranking and pumping viscosities
and a minimum kinematic viscosity at 100C. Single grade oils without the
letter W are based on a set of minimum and maximum kinematic viscosities at
100C and a minimum high shear rate viscosity at 150C. The shear rate will
depend on the test method. Multigrade grade oils are defined by both of
these criteria....
The W is just a designation of one type of testing vs another.

What is the viscosity of the various weight oils? The definitions are as follows:

From SAE J300, viscosities at 212 F...

20, range - 5.6 to 9.2
30, 9.3 - 12.4
40, 12.5 - 16.2
50, 16.3 - 21.8
60, 21.9 - 26.1

By a modified analysis the min. viscosity at 302 F...

20, 2.6
30, 2.9
40, 2.9 - 3.7
50, 3.7
60, 3.7

Note again that the difference between the 20W and 60 weight oils at 302 F
is only about 1 (one). Whereas the difference in viscosity at 104 F is 120
units. The 20W has a viscosity of 40 and the 60W a viscosity of 160. The
difference at startup is even higher, probably 250 or 300.

The American Petroleum Institute, API, and Society of Automotive Engineers,
SAE, have rated engine oil performance over the years. We have seen the
ratings go from SA, SB, SC, SD, SE, SF, SG, SH, SJ, SL with SM to follow. SI
and SK were eliminated as they are used by other businesses. There are over
3 dozen tests that oil now must pass in order to make the next higher rating.
The tests are defined by the American Society for Testing and Materials,
ASTM. Some tests have progressed to a zero tolerance level. For example
there can be no sticking of any piston rings any more. I will compare the SL
rated oil to the previous SJ oil in a few categories. For simplicity I will skip
the units of measurement:

.......S J........S L......

.......30........20......maximum cam plus lifter wear
........9.........7.8.....sludge build up
........5.........8.9.....varnish rating (more is better)
.......60.......45.......high temperature deposits
.......17.......10.......high temperature volatility

Other categories include: Resistance to rust, resistance to foaming,
resistance to oil consumption, homogeneity and miscibility, flow reduction
with varying amounts of absorbed moisture, gelation index and others.

As one can see just going from the previous SJ to the current SL rating is a
significant improvement. I cannot wait to get the upcoming SM oil into my
cars.

Regarding cool whether gel formation, a small except from SAE j300 1999:
4. Because engine pumping, cranking and starting are all important at low
temperatures the selection of an oil for winter operation should consider both
the viscosity required for oil flow as well as cranking and starting, at the
lowest expected ambient temperature.
Pumping viscosity is a measure of an oils ability to flow...during the initial
stages of operation. Test in ASTM D 4684. ....samples are tested after a
slow cool cycle. This cycle has predicted as failures several SAE 10W-30 and
10W-40 oils which are known to have suffered pumping failures in the field
after short-term (2 days or less) cooling. These field failures are believed to
be the result of the oil forming gel structures that result in excessive yield
stress and viscosity of the engine oil...
A.2.1...After preliminary warming, the sample is subjected to a controlled
temperature/time cycle over 5 1/2 to 7 days. The cycle
reproduces ...instability or reversion which has occurred during storage of oils
in moderately cold cyclic conditions. Recent work shows relevance to engine
oil pumpability failure. Oils exhibiting pour reversion have solids resulting from
wax gel formation, at temperatures significantly higher than their ASTM D 97
pour points.
Extracted, from ASTM D 4485-03 Standard Specification for Performance of
Engine Oils, copyright ASTM International, 100 Barr Harbor Drive, Wets
Conshohocken, PA 19428, USA.

My point is that tests are not just laboratory concoctions. They design tests
to match real life conditions.

I use 5W-20 Pennzoil mineral based multigrade oil in my Expedition as it has
many of the low temperature characteristics of higher weight synthetic oils.
My '04 manual states that the SUV is delivered with a Ford semi-synthetic oil
and although regular oil can be used they recommend a semi or full synthetic
oil. For the differential gear oil they used 75W-140 in my �98 Expedition but
now recommend 75W-90.

Please note that it makes no difference what oil you are using. The 0W-20
Mobil 1 that is SL rated meets the same criteria as that SL rated 10W-30
synthetic or mineral based Pennzoil. That SJ or in particular that SH oil some
people are looking for (from their older automotive owners manual) is no
where near as good as any SL oil of today. Always use the most currently
available, highest rated motor oil, even in the oldest, most worn engine. You
may require a thicker grade but just make sure it is SL rated.

The SH rating was used in oils starting 1993. The SJ rating started in 1997
while the SL became effective in 2001 oils. According to ASTM D 4485, SL
rated oils are superior to previous oils and from:
X2.3.1 and 2: SL oil is for use in current and all earlier passenger cars, sport
utility vehicles, vans, and light trucks. This SL rated oil can be used in
engines requiring SJ and all earlier categories.

See: American Society for Testing and Materials- www.astm.org
........Society of Automotive Engineers- www.sae.org
........American Petroleum Institute- www.api.org

**collector240sx** · 11-14-2009, 08:26 PM

Motor Oil 108
Chapter Eight. Odds and ends.

I have some stories that I collected. First, my architect drives a big SUV. He
was running with Mobil 1 brand 15W-50. He changed it to Pennzoil Multigrade
(mineral oil based, non-synthetic, cheap) 5W-20 at my suggestion. His gas
mileage went from 10 to 13 MPG around town. What really impressed him the
most was the �robust� increase in �get up and go.� He changed from a thick
synthetic to a thin mineral oil. His venue is stop and go city traffic in Florida,
mostly short trips. The oil just never got that hot to require a 50 weight oil.
Short trips means that the oil temperature never gets up to the normal
operating range. It was too thick on short trips and too thick when it did get
up to temperature.

The lower temperatures he was seeing occurred because of reduced friction
and internal drag and higher oil flow.

One of the members of the Ferrari Chat web site went from a 40 to a 30
weight oil in his Ferrari 355 for racing in Texas. He noticed a drop in
temperature but no change in oil pressure. This may seem odd but really
makes perfect sense. Since the 30 weight oil is thinner he got better flow
and therefore better cooling. The oil was at a lower temperature so it was
not as thin than it would have been at the previous higher temperature.
Cooler engines last longer. Fact: The higher the temperature, the greater the
wear, all other things being equal.

People say that their old car manual says to use a 10W-40 so they would
never think of using a 0W-40. Again, both are the same viscosity at normal
engine operating temperature. The 0W-40 just does not thicken as much
after you turn off your engine. There are now several cases when manuals
for older cars have been updated to reflect this. My 550 Ferrari Maranello
manual said to use 5W-40 yet the 575 manual says to use the 0W-40. The
engines are the same except the 575 has more BHP. It has better
acceleration and more top speed. The engines have the same tolerances.

All manufacturers I have seen are specifying 0W-XX or 5W-XX oils now.
Honda, Ferrari, Ford, Mercedes, Porsche, and others specify a 0 or 5W-XX oil
to mention a few. These are appropriate for all engines of all ages of all levels
of wear. This second number is the only thing that may change with an older,
lose or worn engine. This can only be determined by experimentation. If you
are using XW-50, go to a 0W-40. If your pressures are still too high go to a 0
W-30 and so on.

When I took delivery of my 575 Maranello I drove for 500 miles then changed
the oil to 0W-30 Mobil 1. There were no changes in operating pressure or
temperature. Starting the engine seemed faster though. I called up FNA and
was told that all new Ferrari cars are delivered with 5W-30 Shell Helix Ultra.
That is when I decided to try the 0W-20 Mobil 1. I could even go to a 10
weight oil as my pressures are still excessive while driving around town. I do
not drive on the track.

What about the break in period? For one thing you could just follow the car�s
manual and gradually break your engine in. Some cars like Ferrari and
Lamborghini run engines and the cars for a period of time before you even
take delivery. They often run up to full power. Some representatives at least
from Ferrari hinted that the traditional break in period was not really needed,
at least in their car.

Most people who buy high powered cars that I have experienced will just get
in there cars and step on the gas fully. They do not wait for the oil to warm
up. Personally I would not mind running full BHP for short bursts during the
break in period but I always fully warm up the engine first.

Older engines may in fact benefit from thinner oil use. Over time permanent
deposits of carbon and sludge build up in the engine oil ways. It is like a
clogging of arteries in humans. We are now all on blood thinners. This is an
area I specifically studied while a general surgeon resident at Chapel Hill.

Thinner oils, and specifically synthetic products are better. Some people say
their engines were �designed� to run on mineral based lubricates. I have not
seen anything to support this theory. The synthetic of the same viscosity as
the mineral oil you are now using will be an improvement. If you go from a
mineral to an even thinner synthetic you may be better off still. The
pressures go up in many older engines because of this �clogging� of the
arteries. Most think this is good but it is really a lessening of flow and
therefore accelerates engine wear even further.

For those engines with excessive varnish and carbon buildup the engine oil
additives of the detergent type may be of benefit. On the other hand you
could just use a thin synthetic oil and change it every 200 miles for a while
and end up with an even cleaner engine. With everything working properly
you may actually need a thicker oil if that engine is overly worn. The thicker
oil would be a disaster however, if the arteries were narrowed from deposits.

Remember, the only difference between a 0W-40 and a 10W-40 is that the 0
W-40 thickens less after you turn off your engine. It is still too thick in the
morning at startup but not as thick as the 10W-40. Yet, they are still too
thick to use until they both warm up to operating temperature at which point
they have the save viscosity, around 13 to 14. Remember that the 0W-30, 10
W-30 and straight 30 weight oils all have a viscosity of around 10 at normal
engine operating temperatures.

There is one more thing. A 20 weight oil is not half as thick as a 40 weight
oil. The real scale is more like the oils having an absolute thickness of 108
and 114. Now it can be seen that the 40 weight oil is only around 10 percent
thicker than the 20 weight oil. The difference is not that much at operation
but at startup the difference is significant. Pressure / flow dynamics go along
with this 10 percent figure. A 30 weight oil should be thought of as having an
absolute viscosity of 110 and a 50 weight oil has an absolute viscosity of 120
. I am talking about operating temperatures.

I thought everyone knew that 90 percent of engine wear occurs during the
startup period because oil is just too thick. Some think it is good to have a
thicker oil for startup since the parts shrink when cold and would
otherwise �rattle.� Sure, your piston diameter will shrink on cooling but so will
the diameter of your bore. The net result is about the same clearance hot
and cold. This is not true for your valves. They lengthen when extremely hot.
In the Murcielago they use shims instead of self adjusting valve tappets. You
need to put a millimeter of clearance there so that after expansion the valve
will not be held partly open when it is supposed to be closed.

If it were true that thicker oils were needed at startup then the
manufacturers would not be requesting oils that thicken less on cooling. They
would just specify that one should use a straight 30 or 40 weight oil.
Instead, over time, they are specifying thinner and thinner oils.

The manufacturers know what parts shrink or expand and the clearance
changes that result. You do not have to worry about this. If it was that easy
to design engines we would all be making them.

I would like to go back to the worry that oil falls off the parts when a car is
stored or sees long periods of inactivity. For the first oil change in my 575
Maranello I drained the Shell and put in 0W-30 Mobil 1. This was at 775 miles
on the odometer. I drove the car home from work, put it on the lift and
drained the transaxle and engine oils. I also opened and drained the oil cooler
and took off every line that is in the oil system. I wanted to get every speck
of the Shell oil out of there. For optimal results you are not supposed to mix
synthetic oils of different brands.

The system takes 12 quarts with a �normal� oil change but took 15 quarts for
this change. It all took about an hour. I then started the engine to check for
leaks. The multitude of mechanical engine noises that followed nearly broke
my eardrums for about 10 long seconds. Then it was suddenly very quiet.
You could hear a pin drop. There was certainly the most possible amount of
surface oil on all the internal parts as the engine was only off for an hour.
But it was not until the oil circuit primed, filled then sent flow into all the
parts that any lubrication was occurring. Hence all oil filters that are
manufacturer certified have back flow limiters to keep the oil filter full even
with the engine off.

Here is an interesting tidbit of information. A 75W-90 gear oil has the same
viscosity as a 10W-40 engine oil at 212 and 302 F. Once again, those
numbers on that oil can are misleading and certainly add to the confusion I
see among automotive enthusiasts. At 75 F gear oils are much thicker than
motor oils. There are no start up issues so pour point depressants are not
added that minimize the thickening with cooling in gear oils.

**collector240sx** · 11-14-2009, 08:29 PM

Motor Oil 109
Chapter nine. Let�s start over.

We have seen that 0W-30, 5W-30, 10W-30 and straight 30 weight oils all
have the exact same viscosity at 212 and 302 F. What about startup
viscosities? Do 0W-20, 0W-30 , and 0W-40 all have the same viscosity at a
75 F startup. The answer is no. The SAE J300 standard allows for this
discrepancy. Here are some examples:

..Viscosity at 75 F startup..

...0W-20.....0W-30.....0W-40
.....40............50...........60

The numbers are not exact but they show clearly that the �0� represents
different startup viscosities. This is unlike the 0W-30, 5W-30, 10W-30 and
straight 30 weight oils that all have the exact same viscosity in a hot engine
= 10 cS.

I would like to comment on the following statements made by a
knowledgeable automotive enthusiast:
�Pressure and flow are tied together with viscosity, but none have anything
to do with lubrication. Lubrication is a property of the fluid, not the force.
The oil pump would pump water just as well, but it would offer no real
lubrication. If we double the pressure, we double the flow. If you decrease
the viscosity to a lighter oil, you increase flow at a loss of pressure. High
flow helps to carry away more heat. High pressure helps to keep metal parts
like the bearings out of contact with each other (scuffing).�

I give you the following example to help visualize what is happening. This
assumes the oil has no internal resistance. In actuality doubling the pressure
will not double the flow but will be slightly less. And thicker oils have more
resistance than thinner oils for all situations. But simplified we get the following:

For a 30 wt oil at operating temperature:
RPM....Pressure..Flow
1,000......20 PSI....1
2,000......40 PSI....2
4,000......80 PSI....4
8,000... 160 PSI....8 The maximum flow because of the oil pop off valve at 90 PSI will be 5

For a 30 wt oil at operating temperature
and a higher output oil pump:
RPM....Pressure..Flow
1,000......30 PSI....1.5
2,000......60 PSI....3
4,000....120 PSI....6 The maximum flow because of the oil pop off valve at 90 PSI will be 5
8,000... 240 PSI....12

If we stick with the same weight oil and increase the oil pump output we will
increase the pressure and the oil flow too. If we double the oil pump output
we will double the pressure and we will double the oil flow (in an ideal
system).
RPM....Pressure..Flow
1,000......40 PSI....2
2,000......80 PSI....4
4,000....160 PSI....8 The maximum flow because of the oil pop off valve at 90 PSI will be 5
8,000... 320 PSI....16

Let us compare a 40 wt oil at operating temperature:
The oil is thicker, has more internal resistance and therefore requires more
pressure to get the same flow.
RPM....Pressure..Flow
1,000......30 PSI....1
2,000......60 PSI....2
4,000....120 PSI....4 The maximum flow because of the oil pop off valve at 90 PSI will be 3
8,000....240 PSI....8

For a 40 wt oil at operating temperature
and a higher output oil pump:
RPM....Pressure..Flow
1,000......45 PSI....1.5
2,000......90 PSI....3 The maximum flow because of the oil pop off valve at 90PSI will be 3
4,000....180 PSI....6
8,000... 360 PSI....12

For a 40 wt oil at operating temperature
with the original pressures:
RPM....Pressure..Flow
1,000......20 PSI....0.5
2,000......40 PSI....1
4,000......80 PSI....2
8,000... 160 PSI....4 The maximum flow because of the oil pop off valve at 90 PSI will be 3

Increasing the pressure while using the same oil will increase the oil flow but
increasing the pressure by increasing the oil thickness will result in less flow.
It takes more pressure to move a thicker oil. When you go to a thicker oil the
pressure goes up because of the increased resistance, and therefore
reduction of flow.

There is more to these graphs but I will contiue with the next chapter.

Furthermore pressure does not equal lubrication. Let us look at a single
closed �lifetime lubricated� bearing. We could hook up a system to pressurize
the bearing. This can actually be done. We could have the oil at ambient
pressure. We could then double, triple, quadruple the pressure of the oil. The
oil is non-compressible. Regardless of the pressure we would have the exact
same lubrication, that of the ambient pressure lubrication.

The physics of lubrication as I said earlier show a 1:1 relationship of flow to
separation pressure. Lubrication itself is pressure independent. I will not go
into the mathematical equations for this.

Even water can be used as a lubricant. This is partly because of its high
surface tension. It is used in many medical devices and other systems that
are under or exposed to water. It is just that water rusts metal parts making
this unsuitable for automotive engines. It actually has a higher specific heat
than oil. It can therefore carry away more heat than oil from bearing
surfaces. In this respect water is a better lubricant than oil.

**collector240sx** · 11-14-2009, 08:33 PM

Motor Oil 201
Chapter 10, The graduate.

I am going to bring up the constant flow pump concept. First, it goes back to
the principal that doubling the pressure of the same weight oil does not
exactly double the flow but it is close. Also doubling the RPM for the same
reason does not exactly double the flow but again it is close.

This shows the problem best:

(A) For a 30 wt oil at operating temperature:
RPM....Pressure..Flow
1,000......20 PSI....1
2,000......40 PSI....2
4,000......80 PSI....4
8,000... 160 PSI....8 The maximum flow because of the oil pop off valve at 90 PSI will be 5

(B) For a 30 wt oil at operating temperature
and a higher output oil pump:
RPM....Pressure..Flow
1,000......30 PSI....1.5
2,000......60 PSI....3
4,000....120 PSI....6 The maximum flow because of the oil pop off valve at 90 PSI will be 5
8,000... 240 PSI....12

If we stick with the same weight oil and increase the oil pump output we will
increase the pressure and the oil flow too. If we double the oil pump output
we will double the pressure and we will double the oil flow.

(C) For a 40 wt oil at operating temperature:
The oil is thicker, has more internal resistance and therefore requires more
pressure to get the same flow. Compare this with (A):
RPM....Pressure..Flow
1,000......30 PSI....1
2,000......60 PSI....2
4,000....120 PSI....4 The maximum flow because of the oil pop off valve at 90 PSI will be 3
8,000....240 PSI....8

(D) For a 40 wt oil at operating temperature
and a higher output oil pump:
RPM....Pressure..Flow
1,000......45 PSI....1.5
2,000......90 PSI....3 The maximum flow because of the oil pop off valve at 90 PSI will be 3
4,000....180 PSI....6
8,000... 360 PSI....12

The situations (A) and (C) are close to real life, assuming no loss in the
system. This is what happens when you change the 30 weight oil to a 40
weight oil in your car:

(A) For a 30 wt oil at operating temperature:
RPM....Pressure..Flow
1,000......20 PSI....1
2,000......40 PSI....2
4,000......80 PSI....4
8,000... 160 PSI....8 The maximum flow because of the oil pop off valve at 90 PSI will be 5

(C) For a 40 wt oil at operating temperature:
The oil is thicker, has more internal resistance and therefore requires more
pressure to get the same flow.
RPM....Pressure..Flow
1,000......30 PSI....1
2,000......60 PSI....2
4,000....120 PSI....4 The maximum flow because of the oil pop off valve at 90 PSI will be 3
8,000....240 PSI....8

At 6,000 RPM the maximum rate of flow has been reached with the thinner oil
(A). When you go to 7, 8 or 9,000 RPM you do not get any more flow. You
only get a maximum rate of 5. The internal forces on the bearings increase
but there is no additional flow of oil.

With the thicker oil you reach maximum flow at 3,000 RPM (C). Worse yet is
that the maximum flow is now only 3. As we increase RPM to 4, 5, 6, 7, 8,
9,000 RPM we get no additional pressure and no additional flow, no increase
in lubrication.

Next let us look at a 20 weight oil at operating temperature. We get the
same flow out of our constant volume pump but the thinner oil requires less
pressure to move through the system. This even goes along with the rule
that we should use an oil that gives us 10 PSI per 1,000 RPM:

(D) RPM....Pressure..Flow
1,000......10 PSI....1
2,000......20 PSI....2
4,000......40 PSI....4
8,000.. ...80 PSI....8

The maximum flow rate has not been reached. If the engine went to 9,000
RPM then the flow would be 9 at 90 PSI, our maximum pressure at pop off.
The engine now has 3 times the flow rate as with the 40 weight oil at full
RPM. The nozzles at the bottom of each cylinder are spraying 3 times the
amount of oil lubricating and cooling this section. Everything runs cooler and
the separation forces in the bearings are 3 times higher.

For engines that redline at 5,000 RPM they usually pop off the oil pressure at
50 to 60 PSI. For engines that go to 8-9,000 RPM the pressures max out at
90-100 PSI. You can now see that you can only get the maximum flow rate if
you follow the 10 PSI / 1,000 RPM rule.

The winner: 0W-20 weight oil for my Maranello. I said earlier that I could use
a 10 weight oil. I actually only run with 185 F oil temperature around town
and the pressures are similar to the 40 weight oil example in (C) above. This
is why I also said that in the racetrack condition, with hotter, thinner (0W-
20) oil I may actually get the optimal results as in (D) above.

Now let us go back to the Ferrari recommended parameters in my 575
Maranello manual. It calls for 75 PSI at 6,000 RPM. The pop off pressure has
not been reached. As we now increase the RPM we still get an increase in
flow rate. This is what we need and this is exactly what they are
recommending. We get our maximum flow at the maximum system pressure,
at about the maximum engine RPM of 7,700. There is no bypassing of the oil.
All oil pumped goes through the system. There is no wasted BHP pumping oil
past the bypass valve back to the oil tank. It is the perfect system.

Finally I will compare a single, 30 weight oil, at normal (212 F) and at
racetrack (302 F) temperatures:

(A) For a 30 wt oil at normal (212 F) operating temperature:
RPM....Pressure..Flow
1,000......20 PSI....1
2,000......40 PSI....2
4,000......80 PSI....4
8,000... 160 PSI....8 The maximum flow because of the oil pop off valve at 90 PSI will be 5

(E) For a 30 wt oil at elevated (302 F) operating temperature. The oil is
thinner at 302 F. It requires less pressure to get the same flow:
RPM....Pressure..Flow
1,000......10 PSI....1
2,000......20 PSI....2
4,000......40 PSI....4
8,000......80 PSI....8 The maximum flow because of the oil pop off valve at 90 PSI will be 9

The hotter (302 F) 30 weight oil is thinner than the cooler (212 F) 30 weight
oil. It has the same flow rate in the constant volume oil pump but at a lower
pressure than the oil at normal operating temperature. This allows for a
doubling of the flow rate at peak RPM. The thinning of oil at higher
temperatures is a benefit. You get more flow, more cooling and more
lubrication.

The 30 weight oil at 302 F has the exact same flow rate and pressures as
the 20 weight oil at 212 F. See (D) above. Therefore, use the 20 weight for
around town driving and the 30 weight on the hot track. You get maximum
flow at each situation.

For YOUR engine, substitute the actual flow at 1,000 RPM. If your engine
puts out 1.5 liters/min. at 1,000 RPM it would put out 3 liters/min. at 2,000
RPM and 6 liters/min. at 4,000 RPM and so on. The maximum flow in (A) would
be 7.5 liters/min. In situations (D) and (E) you would get a maximum of 13.5
liters/min.

Conclusions:
The reason that multigrade oils were developed in the first place was to
address the problem of oil thickening after engine shutdown. Over the years
we have been able to reduce the amount of thickening that occurs. Never-
the-less there is no oil that does not thicken after you turn your engine off.
This is why we have to warm up our engines before revving them up. Engine
designers always pick the recommended oil based on a hot engine and hot oil.
There is no issue with oil thinning as they are both matched when hot. The
problem is oil thickening when the engine cools.

Cold engine showing very high pressures because of the thickened oil at startup:

For a 40 wt oil at 75 F at startup:
The oil is thicker, has more internal resistance and therefore requires more pressure to get the same flow.
RPM....Pressure..Flow
1,000......60 PSI....1
2,000....120 PSI....2 The maximum flow because of the oil pop off valve at 90 PSI will be 1.5
4,000....240 PSI....4
8,000....480 PSI....8

At 1,500 RPM you reach the maximum oil flow rate and if you run to 8,000
RPM it is the same rate. The flow cannot increase and it is insufficient. This
is why we must wait until our oil temperature comes up to 212 F or higher.
The maximum flow rate in this case will then double, up to 3. To get even
more flow in our test engine you need to use a lower viscosity grade.

If you have absorbed and digested the information here you should be able to
pick out the proper operating oil weight for your car, be it a 30, 40, 50 or
even 20 weight oil. I have always used oils that were a grade thinner than
recommended even though many use a grade thicker than recommended. I
showed evidence that the starting grade should always be 0 or 5 (0W-XX or 5
W-XX for thicker oils). If you want the best protection and highest output
from your motor use a synthetic based oil. The actual brand is not as critical
as the viscosity. The rating must be SL or the upcoming SM rating. Change
your oil every 3 - 5,000 miles and at least every spring.

Final examination to follow later.

THE END

**collector240sx** · 11-14-2009, 08:36 PM

Little test if you want to try (answer in the next post)

Motor Oil Midterm Examination
Answer questions without looking back. This is a closed book exam. Base your answers on the information provided in these past chapters.

1- At normal operating temperature, 212 F, a straight 30 weight oil has a viscosity of how many centiStokes?
A- 3
B- 6
C- 10
D- 20
E- 30

2- While racing at 95 F, mid-summer in Florida, which of these synthetic oils gives the best protection at 302 F oil temperature?
A- 0W-40
B- 5W-40
C- 10W-40
D- Straight 40 weight
E- They are all exactly the same

3- While starting up your car at 75 F, mid-winter in Florida, what is the approximate viscosity of a straight 10 (ten) weight motor oil?
A- 3 cS
B- 6 cS
C- 10 cS
D- 20 cS
E- 30 cS or higher

4- The biggest problem with mineral based motor oils with long term use is:
A- Thinning
B- Thickening
C- Loss of VI (viscosity index) improvers
D- Both A and C
E- None of the above is correct

5- Which of the following mineral based motor oils are still too thick at a 75 F startup temperature?
A- 20 weight
B- 10 weight
C- 5 weight
D- All of the above
E- None are too thick

**collector240sx** · 11-14-2009, 08:36 PM

answer (mid term)

Answers to the Oil Midterm Exam
I feel these were all difficult questions. You would be doing well to get 3 correct.

1- At normal operating temperature, 212 F, a straight 30 weight oil has a viscosity of how many centiStokes?
A- 3
B- 6
C- 10
D- 20
E- 30
The correct answer is C- 10 cS.

2- While racing at 95 F, mid-summer in Florida, which of these synthetic oils gives the best protection at 302 F oil temperature?
A- 0W-40
B- 5W-40
C- 10W-40
D- Straight 40 weight
E- They are all exactly the same
The correct answer is E- They are all exactly the same.

3- While starting up your car at 75 F, mid-winter in Florida, what is the approximate viscosity of a straight 10 (ten) weight motor oil?
A- 3 cS
B- 6 cS
C- 10 cS
D- 20 cS
E- 30 cS or higher
The correct answer is E- 30 cS or higher.

4- The biggest problem with mineral based motor oils with long tern use is:
A- Thinning
B- Thickening
C- Loss of VI (viscosity index) improvers
D- Both A and C
E- None of the above is correct
The correct answer is B- Thickening

5- Which of the following mineral based motor oils are still too thick at a 75 F startup temperature?
A- 20 weight
B- 10 weight
C- 5 weight
D- All of the above
E- None are too thick
The correct answer is D- All of the above

**collector240sx** · 11-14-2009, 08:39 PM

Now exam (for those who want it)

Motor Oil Final Examination
Answer questions without looking back. This is a closed book exam. Base
your answers on the information provided in these past chapters.

1- While starting up your car at 75 F, mid-winter in Florida, which of these
synthetic oils provides the least startup resistance, minimal battery and
starter motor load?
A- 0W-20
B- 0W-30
C- 0W-40
D- 0W-50
E- They are all exactly the same

2- While vacationing in Orlando, it is 104 F mid-summer in Florida. The rental
car company put a straight mineral based 30 weight oil in their car because
they wanted the operating temperature viscosity to be at 10 cS. What will
be the approximate viscosity of the oil when you start up your engine now?
(Closest answer)
A- 10 cS
B- 20 cS
C- 30 cS
D- 100 cS
E- 400 cS

3- While vacationing in Florida you are able to race your car at the Sebring
track. At an oil temperature of 302 F what is the approximate difference in
viscosity between a 20 and 40 weight oil. (Pick the closest number)
A- 1
B- 10
C- 20
D- 40
E- 400

4- Assume there are no losses in the system and your oil pump is truly
volume based. Also assume there is no cut off pressure valve and you are
using a 40 weight motor oil. If at 1,000 RPM your pressure is 30 and your
pump output is 1 (one), what will the pressure and output be at redline, 8,000
RPM?
A- 240 PSI, flow = 8
B- 180 PSI, flow = 8
C- 240 PSI, flow = 4
D- 180 PSI, flow = 4
E- 120 PSI, flow = 8

5- Water can be used as a lubricant.
A- True
B- False

6- If you increase the pressure in a bearing, all other things being constant,
the force of separation between the parts increases.
A- True
B- False

7- The best weight oil for racing any Ferrari or Lamborghini is a 40 weight
multigrade synthetic oil like Mobil One 0W-40.
A- True
B- False

8- For my Maranello 575 the 0W-20 weight Mobil 1 oil is actually too thick for
my driving conditions.
A- True
B- False

9- The major problem with engine oil is that it thins with increasing
temperature.
A- True
B- False

10- Your 1993 sports car manual states to use an API / SAE SH rated 10W-40
mineral based motor oil. Your engine has only 1,550 miles on the odometer.
On your next oil change it would be better to use a SM rated 0W-40
synthetic oil.
A- True
B- False

11- According to SAE J300 a 30 weight oil has a viscosity of between 9.3
and 12.4 centiStokes at operating temperature (212 F).
A- True
B- False

12- In my list of recommended oils what did I list as the best mineral based
motor oil in the 50 weight class?
A- Pennzoil multigrade 20W-50
B- Castrol GTX 15W-50
C- Red Line 10W-50
D- Valvoline Durablend 0W-50
E- No oil was recommended

13- You are running 5W-40 Shell Helix Ultra fully synthetic motor oil in your
Mercedes Benz. You are in a K-Mart shopping center and checked your oil
and it is 1 1/2 quarts low. You will need to add one can of oil. Which of the
following is the best choice.
A- Mobil 1 - 0W-40
B- Pennzoil Synthetic 5W-40
C- Red Line Synthetic 5W-40
D- Castrol Syntec 0W-30
E- Shell mineral based 10W-40

14- Motor oils that are labeled �for racing only� should not be used for
everyday driving because:
A- They do not have detergents
B- They may have harmful levels of some additives
C- They are generally unrated, there is no SJ, SL or SM approval
D- You would have to take your engine apart and clean it periodically
E- All of the above

15- ASTM stands for:
A- Automotive Standards and Test Methods
B- Automotive Society for Tooling and Machining
C- American Society for Testing and Materials
D- American Standards Trade and Manufacturing
E- Society for American Standard Testing Methods

16- If your engine is running too hot at higher RPM one thing you can try to
bring the temperature down is to use a thinner oil.
A- True
B- False

17- Oil with a startup thickness of 100 (at 75 F) that becomes the
appropriate thickness of 10 when fully warmed up (212 F) is called a 10W-30
weight motor oil.
A- True
B- False

18- A main advantage that the synthetic has over the mineral based oil of
the same grade is the ability to lubricate better at startup.
A- True
B- False

19- In ASTM D 4485 3.1.4: Engine oil is defined as - - �a liquid that reduces
friction and wear between moving parts within an engine, and also serves as a coolant.�
A- True
B- False

20- I am (single best answer):
A- Surgeon
B- Biochemist
C- �Halfass mechanic
D- Absurdly interested in motor oils
E- All of the above

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