Tii LSD Gear Oil in FD diff?
 

I have searched this in the 3rd gen section as well as the second gen section and I cannot find any definitive information.

I am just looking for the recommended gear oil and additive to use in my Rear end. I've got a 93 FD with an s4 Tii limited slip. I am putting it back into the car tomorrow and want to know what type of fluid to run in it.

Thanks in advance for the help and direction.

Josh

Use a gear oil suitable for clutch-type LSDs. That means it will include a friction modifier.

Dave

I've had no problems using Lucas 75/90 on my GSL-SE which also had a clutch-type LSD

so a redline 75/90 would be suitable?

The challenge with clutch-type LSDs (such as the TII diff) is getting the right lubricity so the plates offer friction but don't get into a stick-slip behavior. The gear oil vendor can only do that well when they are familiar with the exact application it's used in, so that means Mazda only. Since I don't think Mazda uses synthetic I would go aftermarket to get the synthetic.

There are two approaches - use a basic gear oil and add limited slip additive until the plates are working well, or use a gear oil that has ls additive already blended in. Both will work, and I suspect you will get your best info from TII diff users since most FD owners don't have clutch packs in the diff. If you race, then the amount of modifier allows you to trade off between torque bias and heat/wear in the diff. For a street car I'd simply use a GL-5 synthetic 75w-90 gear oil formulated for LS applications and if things behave well in back leave it at that.

Redline 75w-90 falls in that category: http://www.redlineoil.com/products_g...5&categoryID=6

Dave

Dave thanks so much for your explanation. This helps allot!

I just did the exact same swap and i used royal purple 75 90 and half a bottle of 75 140 (by accident) i didn't even know they made 75 140, it says the exact same thing on the container as the 75 90. Its working great though. I'm glad i did the swap