I have a 2004 Dokota.
Does anyone know what differential lube to use in an anti spin rear end. I tow a small boat and need to know what lube to use. What weight ,how much do I need and if an additive is needed

Thanks

 

A lot of folks on this forum like synthetics. I'm old school so I stick to the factoryrecommended SAE 75w-90, GL-5 gear lubricant. My 8.25 rear diff holds about 4.5 pts, a 9.25 rear holds closer to 5 pts. It should be within 1/4" of filler hole. You need one bottle of MOPAR hypoid oil additive friction modifier for posi rears. I just had my 60k mile service and the dealership forgot the friction modifier. The clutches got tight and it was like I had a locker on the rear axle! Moral of the story: make sure the shop doesn't forget to add the friction reducer. Its a small bottle, only about a fourth of a pint.

 

If you install synthetic oil do you still use the additive?

 

I'd give the dealer a call, but my guess is the additive is necessary regardless of the oil type you use.