Had dealer flush differential, or replace oil. Noticed he did not put in posi additive. Is this a problem for a 2002 WS6 Trans am?

 

Most newer Oils for rear differentials contain the need friction modifier. But with out knowing which oil specifically was used it hard to say.

 

If your rear is still the factory Torsen diff, you DO NOT want to add any friction modifier ("posi additive") to the rear lube. This friction modifier is needed only for clutch-pack type differentials that rely on friction between numerous layers of clutch material for the posi action. I've heard that the OM is not accurate in its requirement to add posi additive. Sounds like your mechanic did the right thing.

 

^ Yep, no need for the additive in a stock 2002 (Torsen) rear. This was only needed for the 1998-and-earlier factory Auburn rears.

It won't hurt anything to add it, but it's not necessary for proper operation of a Torsen style diff.

 

Thanks for the info.