Can someone please point me to a thread or video of how to do both front and back differentials on my '14 Cummins? Thanks

 

Unless they've changed something, you pull the bolts out of the cover, break the seal and drain the fluid, then clean up the mating surfaces, apply new sealant, and then refill with the appropriate fluid.

My 08 used 75w140 in the rear, 75w90 up front, synthetic gear oil, no limited slip modifiers needed.

As far as the sealant goes, if you use RTV, you'll want to choose wisely. Permatex makes a bunch of different stuff, my personal choice is The Right Stuff.

RTV is supposed to be allowed to cure for hours before adding fluids. TRS is not silicone based, it's an elastomeric rubber, and it's ready for use in minutes.

If you go with RTV, they make one formula specifically for gear oil. It's not an ULTRA product though, so as new fluids come out it isn't updated for compatibility. The ULTRA line of RTVs are.

 

A 14 How many miles?

 

The '13 + use a reusable rubber gasket on both front and rear diff covers.

No need to use RTV.

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