I am about to change the gear lube in the rear end of by 94 Z28 A4 with 3.23 gears. My question is if I use synthetic gear oil in my rear end that already contains limited slip additive do I still have to use the GM limited slip additive? Also what is a good gear oil?

Thanks

 

Mobil 1 75w90 gear oil + GM limited slip additive found at the GM parts counter has always worked perfectly for me.

If you buy gear oil that already has the limited slip additive in it, I would try it out first without adding anything. If it squeals/pops or otherwise acts like it shouldn't then go to the dealer and get some additive.

 

Im using standard 75w90 cheap stuff and GM limited slip additive. Works fine.

 

Same here...

 

I run 80W140 it provides better protection for the ring and pinion gears under hard launches.



does 90W-180 oil exist?--cause for some reason those numbers are stuck in my head. I don't know why though, maybe i read about it--or maybe i'm just crazy and it doesn't exist.