TireSmoke.org

I've never changed the lube in my Chevelle since the rearend was put together in the early-mid 90s. I thought it might be beneficial to change it out soon. The posi is a little grabby-clunky when turning, because I never added the "posi-lube" when it was put together all those years ago.

I have a few bottles of un-opened gear lube. I'm 90% sure they moved with me from the old house to the new house, which makes them at least 9 years old, but probably a little older than that.

I know GMJohnny's mantra is "any oil is better than no oil"

-Dave

I would run it!! I can't think of a reason that oil would go
bad. As long as the bottle is sealed, I think you are good.
We've used oils at work that are really old and they work
fine. Although, sometimes we "fill it with that old stuff"
it's because there is no oil left, and any oil is better than
no oil at all. I'd make a concerned effort to put posi lube
in it if you change it. I'd also consider leaving the old lube
in and just add posi lube. A rear end is a closed system and
really can't get outside elements in it if it is sealed the correct
way.

GM

If it's not synthetic, I would recommend the switch. They make synthetic lube with the posi additive already in it. Free HP in my opinion. But to the original question, I'm sure the old stuff will still function as new.

-BP