Gear Oil - Additive Amount

[Andrewg]

I'm getting ready to change the oil in my 8 3/4. It's got a sure grip in it, so I know I need to add some of the additive. My question is how much?

[jimynick]

Dr.Diff sells the Ford additive and you can still buy the Mopar one from the dealer. In both cases, I believe you add the whole bottle and top up with gear lube. 

[headejm]

 

I put synthetic gear oil in my 8.75 and supposedly you don't need an additive. When backing up, the dif would "clunk" like it was grabbing. Added a bottle of the Ford additive and the noise went away.

[Andrewg]

Thanks guys!