news2me

If I need to top off my differential lube, what lube do you guys recommend. I'm not getting it from on-line vendor, I'll run to my local parts house. I have no clue what brand I have in there now, so can mix one with the other... As long as its for a posi-rear???

Sigforty

If you don't know what's in there you probably would be better off siphoning it out and replacing it. What ever you choose you will probably need one bottle of Gm posi additive.

I personally went with Tom's choice of Lucas 75w140 gear oil. I found it at the local autozone. The diff took about 1.5-2 quarts.

Iceaxe

What is the reasoning behind the 75w-140 gear oil? Doesn't GM recommend 80w-90?

Sigforty

You would have to call and ask Tom's differentials. I just went with what he recommended. I am not sure but Gary may use the same oil.

jim2527

I went with whatever name brand the local parts store had in stock and added the appropriate amount on GM additive.

It may not make any difference but I drained the diff, refilled and drove around until it was hot then drained it again in hopes of thoroughly flushing the diff.

Tampa Jerry

If the rear has posi traction, don't forget to include a bottle or two of GM posi additive. Jerry