We all know that using GM’s synthetic differential fluid is crucial in our rear differentials (GM part numbers #12378557 in the USA or #88901362 in Canada). Couple of days ago, I have found this technical bulletin from AMSOIL that specifies their alternative for QS differentials. The bulletin says “AMSOIL Severe Gear Synthetic 75W-90 (SVG) contains all limited slip characteristics required by Dana for QUADRASTEER differentials.” And “AMSOIL limited slip additive (ADA) should only be added if differential chatter occurs.” However, I would add the additive anyway, chatter or not.

I will use the GM fluid as long as it is available, but it good to know that there is an alternative.

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Thanks for the post Ken.