ah good, thanks for the replies on this I do appreciate the advice and no better person to get it from IMO. Gives me some peace of mind on this issue. I did find the car a bit more sluggish after I put in the 75w140 in place of the 75w110, much like you describe so mpg's will likely be lower. Thanks again.

 

what about in a stock diff?

you are running one with what i assume is all the goodies. what about one thats bone stock. would you still run the 75/110 vs the straight 90wt?


also would it hurt the diff to use LSD additive?

 

75/90 is fine to use for the everyday daily driver. 75/110 is better and a good choice for auto x and performance rears. 75/140 80/250 SAE 190 SAE 250 are also used for performance and high demand rear ends.

There is no need for LSD additive in a stock S2000 rear. Our LSD is gear driven not clutch driven so need for LS additive.

 

as you may know the SAE90 spec which was in place when the S2000 was first engineered (1999 and earlier) is now equal to today's 110 vicosity, as the viscosity standards have changed since then. I would not use anything lower than 110. The 75w110 (using Amsoil's specs) would be a perfect match for the S2K requirement being in the middle to high end of the old SAE90 viscoity range. I find many of the 75w90 fluids on the market today are on the thinner end of the SAE90 viscosity range.

 

Thanks very much for the quick reply

 

Hey Ben,
I'm getting a diff fluid change up here in NW FL and want to be sure I've got your mixture correct for 4.56 rear you built for me.
your original e-mail with diff pics indicated 70% 80/90w and 30% Lucas Stabilizer. Is this formula still good, or do you have a better mixture now?
I read the posts above which seem to indicate straight 75/140 is just as good and maybe even a little quieter.
Thanks.