This is slightly bogus but, Can someone help me out by telling me how to change my rear differential oil. I have a 2004 F150 crewcab 4x4 3.73, also should I change the front? I want to use redline 75w 140, but again front and back or just back and is there another way to drain the oil other than taking off the cover? Or is it best to take the cover off and buy a new seal and sealant for the reinstall. Thanks, Ken

 

Pulling the cover is only way in the rear. The front has a drain hole. No need to buy a new gasket, just apply a liberal amount of black RTV to the surface after a good cleaning. Also, make sure to put a small amount of RTV around the threads on the drain plug in the front, so there are no leaks...

 

Thanks midnight 99. So, should I use the same oil as the rear when I change both or is the front sometime that is rarely done. I have about 45,000 on the truck. Oh, another dumb question. The front has the drain plug is that also the fill hole for the front. Thanks, Again.

 

The drain hole is not the fill hole. The fill hole is little higher (above the horizontal centerline of the housing.). The front does still spin while the truck is being driven, but there is really no load on the ring and pinion because they are not "driven". This does not generate as much heat which means longer oil life, but I would change both. 75-140 in both and friction modifier for the rear if it is limited slip..

Adam

 

midnight99, the front does not spin on an 04 up. They have Warn IWE's which unlock and lock the hubs by vacuum.
Salty6828, if you change the rear and you have limited slip, make sure you add a friction modifier. You do not need this for the front as it is an open diff.

 

Thank you for the correction, I was not paying attention apparently..