Guys,

I am in the middle of upgrading/rebuilding my diff and exploring the option of adding a diff cooler with manual switch to turn on/off at particular temp.

Firstly, what is the optimal operating temp for the S2000 diff.

I think it would be sub 100C, the rationale behind this is I am installing an OS Giken LSD, along with 4.77 diff gears, and a Spoon enlarged diff casing. Looking at diff fluid oil, everyone reccomends the OS Giken diff fluid. The weight of this is 80W-250. Contrary to OEM/Redline that I currently use is 75W-90. The thickness is incredibily heavy compared to OEM. It seems to be the general concesus for people to either 75W-90 or 75W-140 for the oem diff, but OS Giken is 80w-250...

I'm not sure if I do need a diff cooler, as since I will be using the Spoon diff casing which triples the volume of fluid in my new diff, as well as using much much thicker diff fluid.

I will be adding a Defi oi ltemp sensor in this new diff. Wish I could find some data on diff temps in stock diff, but no one has showed any data even though this car is 15 years old

Thoughts?

 

Most lubricants work best at around 171 F or around ~80c This is just general rule of thumb, as the second number in a multi grade lubricant is measured at that temperature. I know the diffs can regularly see 120-150c and above during hard driving.