whats the best rear end fluid to use?

 

GM Synthetic and GM additive unless you have a Torsen rear .

 

Royal Purple.

 

Almost every shop I've ever done business with uses Redline.

 

I just had my tranny and rear end done with Amsoil, and on the highway there is a noticable difference in how the car feels when you let off of the gas. My car is an A4 with 3.23's, and at 60 mph if I shut off the cruise it would feel like I threw out an anchor. Not any more. The car doesnt decelerate nearly as quickly as before. This is not just my imagination either. There are a couple places that I drive through that I had a "spot" where I shut off the cruise and the car would slow enough that I would be down to the reduced limit by the time I hit the sign. I have had to adjust my "spots". I am sold on the stuff now.