I recently had my rear diff oil changed, and had an Amsoil posi-additive added because I was hearing my posi- rear end chatter when going slow, slightly off from straight. That did the trick, until I needed to move only a few hundred miles later. The move was 1600 miles so the rear-end no doubt got hot- could the additive have broken down? Any idea of whether I should just add more? Is the GM additive any better?
Thanks,
-Mike

 

I have never found an additive that worked like the gm one. I would stick with what is designed for your rear. That stuff quiets down rears that I thought where just trashed.

 

change the fluid out again and use the gm additive.