im replacing a bent axle shaft and was quoted 80/90 from a repair shop but my chiltons says i need 75/90 im at a loss i did a search and saw people talking about an additive i have a 8.6 10 bolt with 3.42 limi slip (one wheel spins if im correct) no G80 or aftermarket posi what would yall recomend i use and do i need an additive

 

Personally I would use 75w90 synthetic but the 80w90 dino or synthetic should be fine.

no posi = no additive

 

Use 75w-90 synthetic.

Jim

 

Mine calls for synthetic 75/90, it's the factory G80 though. I thought that all the factory rear diffs from 99 on up were using 75/90 syn, but I could be wrong.