I have a s5 turbo II rear end and I wanted to know what is a good fluid to use. Also I will be doing some drifting with this car. and do I need to use a additive to the fluid.

 

I think i put 80w90 in mine or something heavier. S5 viscous....dont waste your time with additives. They dont do anything. The viscous lsd is a sealed unit as in the disks never come in contact with gear oil. You still want to use some heavy gear oil for the ring, pinion and carrier bearings.

Hope this helps.

 

I used Wal-Mart brand 90w gear oil...made it stop whining, so I am thus pleased. Some people prefer Redline and such but to date I've tried many different brands and saw no change between them...thus, I've come to the conclusion that the rear end is more about maintenance and care than brand of oil.

My current car, however, had never had the rear end serviced and the oil that came out was the consistency (and color) of pancake batter. I ended up running a 5wt hydraulic oil in the rear for five miles of very light use which flushed the rest of the old crap out...then filled with the proper weight.