petes74ttop
Well-known member
I'm going to change the differential oil, can I use Trans X additive, from the auto parts store, or do I have to get GM's additive? Is 8 oz of additive correct and what weight oil should I top it up with? PG.
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...Forget the aftermarket stuff....GM additive...GM Diff Lube...
Forget the aftermarket stuff. You want to suck out all the old lube with a suction gun, add a bottle of the GM additive, then fill it with GM Diff Lube or a brand-name 75W90 or 80W90 GL-5 diff lube and do some low-speed figure-8's in a parking lot to get the fresh lube and additive inbetween the Posi clutch plates. That's what it was designed to work with - you don't need any of the hot-rod whizbang miracle race lubes.