UB2SLO

iTrader: (13)

My 98 Z28 just turned over 100K and I know its time to change the gear oil, The rear end is still stock, If heard Royal Purple is good but what weight and how much do I use, and do they make the posi additive?

Thanks

Gary Z

Capacity is 3.5 pints so you need to purchase 2 quarts of any synthetic 75W-90.

Sudz

iTrader: (3)

Depends on your differential if you have the auburn then dont get a synthetic.. get regular differential fluid 75w90, and 1 bottle of genuine GM limited slip additive. If you have the torsen differential use a synthetic.
I have the auburn so i used valvoline 80w90, and a bottle of gm limited slip additive and it works great.