GM Rear diff fluid
Joined: Nov 2001
Posts: 34,659
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From: Schiller Park, ILL Member: #317
1998 was the last year for Auburn posi as the base/stock rear, and this unit calls for conventional (non-synthetic) 80w90 lube with a bottle (4oz) of the GM limited slip additive (can be purchased directly from GM); the additive is required for this rear. '99+ received a Torsen limited slip that calls for 75w90 synthetic and the additive is optional (though GM technically still recommends it in the service manual.)
You also need a set of nose plugs. (The stuff smells really really bad.)
You can also get the additive on the shelf at parts stores. I got some at AutoZone that said it was specifically compatible with and met the GM spec.
You can also get the additive on the shelf at parts stores. I got some at AutoZone that said it was specifically compatible with and met the GM spec.
