83Hurst#1812

Just purchased this car ,,it hasn't been registered or driven regularly since 1988...It's running good and driving ...In process of going through it and flushing and changing every fluid..It's time to do the rear diff...My question is ,,,what is everyone using for fluid ?? Book calls for 80w-90,with 4oz of LS additive...I get that ,,what i need to know is..is it ok to use ,,say a mobil one or valvoline gear oil for limited slip differentials..one that says there is no need to put in the additive... ?

What iseveryone else using these days ??

Thanks,
Erik

monzaz

NO Need for special stuff.

80/90 any brand and YES you must use the additive - use GM brand.

NO TRICK fluid here. AS long as the level is kept up to correct level it will last you the rest of your life.

Jim
J D

83Hurst#1812

Thanks Monzaz,,,picked up some GM additive today...Know i can't go wrong going by the book

Erik

monzaz

YEP, THAT is how the rears are set up also. stay by the book you can not go wrong. JIm

Allan R

What difference does it make whether GM A.S. Additive or not? I don't see they have any special formulation that others don't. Only thing I do see is they cost more though.

monzaz

I do not know BUT it always seems to solve the chattering problem than others... With the steel clutches and or cones type posi units it JUST WORKS. Jim

So if you want to try others that is fine. But if it does not work that was money you just blew anyway... I can tell you the fluids are different from Ford to GM etc. FORDs posi additive totally smells terrible the second you open that bottle it will knock you on your BUTT. Jim

Allan R

I bought the additive from NAPA. - House brand.