New owner of 1990 GTR - Service questions

[menace]

Hello,

This is the car I picked up from a member on here:

skyline GTR 1990 Single turbo


It now has a meth injection setup and boost is up to 25 psi as per the seller its at 620 awhp. Here are the fluids I'm planing to use in it:


1) Engine: Royal Purple 15W40

2) Transmission: Royal Purple MAXGEAR 75W90

3) Transfer case: Royal Purple ATF MAX

4) Front Diff: Royal Purple MAXGEAR 75W90
- Manual says to use 85w90, but I can't find this. RP sells it by the 5 Gal pail. Redline has nothing like that. Is this safe to use?

5) Read Diff: Royal Purple MAXGEAR 75W90
- Manual says to use 80w90, but I can't find this. RP sells it by the 5 Gal pail. Redline has nothing like that. Is this safe to use>

6) Which fluid for the ATTESA? Nissan Power Steering Fluid 10130-89901A? I'm confused about this because the description posted on here for that is "Auto Trans Fluid Special Blend Matic-D", which I think is ATF fluid, no? Is that an error on the description?

7) Clutch: So far I have flushed the clutch lines, got a DOT 3 brake fluid in there. Is the the best choice?

8) Brakes: Service manual says to use DOT 3 brake fluid or more specifically some Nissan specific stuff, forget the name, but that is written in '90, so what are you guys using now? Won't be tracking this until next year and not driving in the winter so something that stores well? Was thinking of just using the DOT 3 again since I have some left from the clutch.

9) Spark plugs are changed, gapped to factory setting which is way wider then what was in there and with this boost probably won't last long. Will take it easy and do e-testing before I change that I think. What gap do you recommend the power this is making at 25 psi?

Which of the above should be done ASAP? Anything else I should check out while I'm at it?


Thank you very much!

[menace]

Finally got to speak to the engine builder and got a recommendation for that. Feel pretty good about the other fluid choices, but concerned about the diff fluid weights (75w90 vs the 85w90 and 80w90 recommended in the manual) and not sure about ATESSA at all since I have found conflicting information regarding that. Any help would be greatly appreciated.