The additive is now called GM PosiTraction Rear End Additive and is available in four ounce bottles at you local GM dealer's parts counter or from Amazon.
Drain the old axle lube, inspect the gearset, and refill the housing using the additive and topping it off with new lube.
Then take the vehicle out to a large parking lot and drive it in tight circles, a few times to the left and then a few times to the right, Keep the steering at full lock and go just fast enough that you're almost spinning the tires. A half a dozen loops in each direction and then repeat.
This also works for the Jeep QuadraTrack transfer cases!! You Jeep guys take note!!
When you're done, drive the vehicle around for a while!! This lets the lube cool a little and washes away the deposits and stuff that build up in the posi assemblies!!
Last edited by Blackwater; 11/14/20 10:29 AM.
