ls1 rear end posi rear

the rear in my car is out of a LS1 6-speed car ... i know that the posi is a little different design ... if i change the diff fluid do i need to put in the additive stuff? and what diff lube is safe to use? i like royal purple but this is the first car with posi that i have had.

Yes use the posi additive. I run mobil 1 oil

I also run Mobil 1 synthetic but I have my auburn still

It it's a Torsen, then you don't need the additive. The additive is only for posi units that use clutches. I also use Mobil 1.

royal purple already has the additive in it i use the gm synthetic gear oil but that is because i get that for free at the dealership i work at but never had any problems with it

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Originally Posted by Spartan7

It it's a Torsen, then you don't need the additive. The additive is only for posi units that use clutches. I also use Mobil 1.

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X2, I swapped my orig 2.73 auburn for a 2000 SS Torsen with 3.42's. Just run gear oil, no additive needed. FWIW, I've been a Redline user in all my toys forever, and it's really good stuff.