Differential and Transfer Case

[OggyOggy]

Howdy Out There!

I have a 2012 4x4 Laramie Longhorn 6.7 Cummins with 37,000 miles on it. I use it to tow a 12,000 lb fifth wheel about 25% of the time. At the end of this month it's going into the Grand Tetons and Yellowstone.

I'm getting ready to replace the rear differential cover with an aFe Power cover because I wanted a bit more fluid in there for the climbs I expect. This means I'll be replacing my fluid. After seeing people talk about variable slip gears I need to know if I have one of these? So, what kind of differential do I have? 10.5? 11.5? Variable slip or not? What kind of fluid do folks recommend?

Given the mileage should I be changing the transfer case fluid as well? If so, similar questions apply.

Thanks!

 

[GrantP]

You may or may not have a limited slip differential in the rear, but either way it doesn't matter with regard to choosing your oil. There are no clutches in the limited slip unit so no additive is required. Grab your favorite flavor of 75w-90 and fill it up.

Yes it's time for a transfer case fluid change too. It's very easy and quick to do. Any brand ATF+4 will do.

Enjoy your trip!