This is my first f 150 and I just went over 50k miles with my 04. I was thinking about changing the diff fluid and transfer case fluid as well. I know the owners manual says 100k but I have always changed these around 30-40k on my other vehicles. Thoughts?
Also, it seems as if I have to crack the diff open as I don't see a drain plug.
I have not looked at the transfer case. Has anyone serviced this? Was it hard?

 

Hi DJ
Welcome.The Diffs on both axles,(if you have 4wd)the rear covers have to come off to drain the fluid as well as scraping the gasket off the surface of the mating area of the diffs.This is very messy so make sure you dress your worst.Make sure you put new gaskets back on b4 you bolt everything back up&add fluid.
Whatever Ford says what fluid to replace by all means listen to the manufactuer.
The transfer case takes a different fluid.I have an 05 F150 STX&the manual calls (for my truck)to use MERCON V fluid which is used in my tranny as well.Crawl under your truck,face the transfer case&you will see two plugs.The lower plug you would unscrew to drain the fluid.Then put the screw back in.. DONT OVERTIGHTEN.Put a wrench to it&just snug fit it.
The top plug is used to fill the case.Pump fluid in until it flows out.Tighten once again.My case holds 2qts of MERCON V.
Again whatever the manual says on changing fluid should be obeyed if you want longevity on your truck.(I think we all do dont we?)

All the best
Pete

 

If you have some extra coin laying around you may want to upgrade your rear diff. cover to a Mag hytec. They cool much better and have drain and fill plugs to make it much easier for future use.

 

I second that Mag Tech diff cover. I have one on my F-350. Love th o-ring seal, plugs, looks. Worth every penny, (all 20,000 of them)!