I'm planning to change out the rear diff fluid soon. Going to use Mobil 1 gear lube. Do I need to add any limited slip additive. I was told to add one bottle that can be purchased from any Chevy dealer. Suppose to stop chatter? Thanks.

Just did mine today. No additive needed 4 quarts

Just changed rear end lube it was pretty dark almost black with a fair amout of sludge on the magnet. 13,500lb axle took 13 quarts:eek: The manual stated 10 pints, needless to say I had to make a few trips to the auto parts store. Glad I didn't use the GM stuff at $27.00 a quart.

Hey i Just changed mine too. It came out Pitch Black, and with a lot of crap, also it had a silver tone to it. Tons of metal shavings. MY posi had been sliping alot while racing. Is there anythign that could have gone bad, or that i could have ruined by not changing my sooner oil? it was the first oil change in 19,000 miles (since i go the truck) and over 250 passes.

If you have (verify RPO code G80 on build sheet) Limited Slip Differential, then the additive is required (that is what makes it slip), otherwise your just grinding it down until it fails. If you don't have Lim-Slip, then you don't need it. If you have "Traction Control using ABS" then you MUST NOT add the Lim-Slip-Dif additive.

Additionally, ALL MDT axles include standard 100% synthetic lube from factory (for long life), and must be replaced with same (GM) or equivalent (other brands) synthetic lube of same grade, to not void warranty.

RF