how do i change the rear end fluild in 04 mountaineer?

Question

what type fluid is needed

Answer 1

You'll need to buy a new rear end housing plate gasket first. It's the plate bolted to the rear side of the housing opposite of the drive shaft.

Put a suitable drain pan beneath the rear end. Loosen all the bolts starting with the bottom. You may have to pry the plate lose with a screwdriver. The rear end lube will eventually start to drain. If you damaged the gasket clean all surfaces and replace with a new one.

Your operators manual will tell you the specification of the lube to use. You could replace the fluid with a full synthetic gear lube if you want to get fancy.

To refill remove the plug on the side of the rear end housing. Re-fill with a small trans funnel or a lube gun.