What type of differential lube should I use on a GM 8.5" 10bolt Posi differential? This is a factory differential, not aftermarket.

Thanks
Renzo

I use Amsoil Severe Gear 75W90 synthetic in the rear ends that I build, but any 80W90 gear oil with the GM limited slip oil additive will work fine.

I just use regular Valvoline which is the same as NAPA. It is cheaper to buy the NAPA brand, but it is the same. I think its 75-90 or something, its their standard weight gear oil. Then add a bottle of the limited slip additive. You can pretty much run any gear oil through them, just dont forget the posi additive!

Absolutely EVERYBODY I've ever spoken to says to use the GM OES supplement with your lube oli-even (gasp!) Ford guys. So who am I to argue with that collective brain power?

Do I run it-heck yeah!

How much of both would it take to get the correct level?

depends on your cover. I **think** it took me 2 3/4 bottles plus the lube.

Absolutely EVERYBODY I've ever spoken to says to use the GM OES supplement with your lube oli-even (gasp!) Ford guys. So who am I to argue with that collective brain power?

Do I run it-heck yeah!
I don't think I'd put EOS in my posi. You must mean the GM posi additive....HUGE difference between the two.

2 quarts plus one bottle of the GM additive should do it if you have a stock cover.