I want to change my differential gear lube with synthetic, what is the best out there and do I need a gasket or is there just silicone? I know I need a can Mopar posi lube with install.

 

IMO Royal Purple and you don't need the friction modifier, it's already in there...

 

You don't need to buy mopar posi lube. Any friction modifier will be sufficient as long as you put the right amount in. Too little can burn up the packs and cause a one wheel peel sometimes and too much can do the same as well as cause chattering from grabbing too much.

Just make sure you have an LSD before you add the stuf. If you have an open carrier..aka..one wheel peel, you don't need the modifier.

 

I will be taking the rear inspection plate off to remove all old dope, do I need a gasket or just silicone?