redeye3745

Usually you put synthetic in the rear differential. Did you add limited slip additive?? On the back cover on the rear has a tag on a bolt. It will have a number on it for the oil weight I believe and if it needs the LS additive it will have an L on it

Jadoun

The Valvoline has already limited slip on it! Not sure of this will work perfectly instead of the synthetic?

dyeguy1212

iTrader: (1)

The LS that comes in diff fluid is not the same as the Ford stuff. You will always need to add the motorcraft additive.