Non posi lube

[CrazyBoutRacin]

I searched a bunch of threads and can’t find anything definitive on this. I’m changing out the lube on my 65 coronet. It’s an 8.75 open rear. What weight should I use. It’s a 4 speed car if that makes any difference. Conventional or synthetic? Thanks!

 

[pnora]

From the FSM

 

[RemCharger]

In a nut shell, 80-90 conventional.

 

[Don Frelier]

This might come up:

 

[Pmayer]

For a stock 8.75 open rear, you can't go wrong with a standard 80W-90 or 85W-90 GL-5 gear oil. Most guys stick with conventional (dino) oil because it's easier on the old seals, but a synthetic 75W-90 works fine if you don't have any leaks. Since it's an open diff, you don't need to worry about friction modifiers. Just fill it until it's level with the fill hole, usually takes a little over 2 quarts.