Ive been using m1 75w-90, but after searching ive found that many ppl suggest 75w-110 or 140. I'd just like an explanation to why this would better match the oem sae 90 requirement.

 

I believe people run it as it's better suited to the way most people like to drive their s2k's. Better suited to shock loads.

 

I run amsoil 75w-140. And amsoil severe gear sad 250. I use 8oz of the amosil 250 and 20oz of amsoil 75w-140. I have a stage 2 puddymod dif

 

hey hypforlife how often do you change your diff's oil? ben recommended every 3000. do you follow his instructions?

 

Im using Amsoil's SG 75w-110.

 

Amsoil 75w 110 here as well.

 

https://www.s2ki.com/forums/index.php?showt...&#entry15962305

I guess I found the answer I was looking for according to this link. 110 falls within range of the old sae 90 requirement.

 

Interesting find, maybe next change I'll try 75w-110. but then I've run 75w-90 for 100k miles w/o issues so why fix what ain't broken.

 

Hey mr choi, where did u get 3000 miles? I change every 6k as I was told from him. I think 6k is fine as amsoil lasts a long time.

 

yeah the old SAE90 spec that was in place when the S2000 was first designed covered a viscosity range of 13.5 to 24 cst at 100 degrees Celsius (with 13.5 being the thinnest viscosity and 24 being the thickest viscosity within the range of the spec). I prefer to go by the old spec range rather than the new SAE90 spec as that was the one that was in place when the S2000 was engineered. Amsoil 75w-110 has a viscosity of about 21 cst at 100 degrees Celsius, which IMO is at the perfect point in the spec range - not too thin. Most 75w90's you buy today have a viscosity of around 13-16 cst 100 degrees, so they are a bit thinner, and closer to the bottom of the old SAE90 spec range in viscosity. We pretty much know that a thicker fluid protects better in these differentials than a thinner fluid when it comes to warm temps. The beauty of the 75w-110 is that it will flow better in cold temps than a conventional SAE90 fluid will, so the best of both worlds analogy applies here. You can kill a diff in cold temps if the fluid doesn't flow well and you drive the vehicle hard, so cold temp protection is important as well, and the Amsoil 75w110 exels at both ends of the temp spectrum. I'm not pushing Amsoil, some other manufactures make 75w-110, I just think this viscosity range is good for our application. Guys running modded diffs and higher hp s2k's might do well with the 75w140 visc.