dengebre

When should I change the rear differential fluid for my 2000 Ford F150 2WD (Axle Code = H9: 3.55 Limited Slip)? It has almost 100,000 miles. The owner’s manual and Ford’s online maintenance schedule make no recommendation (other than to use SAE 75W-140, but no interval).

Thank you in advance for your help.

white89gt

IMO, it should have been done by now. I do mine every 30K. Some say Ford says 100K, but that's just too long for me, personally.

EDIT: By the way, Limited Slip axles also require a bottle of Friction Modifier. Don't skimp, and use the Motorcraft stuff. It's better. Also - there are some gear oils, such as Lucas, that say no modifier is needed. Still use the Motorcraft stuff.

EDIT 2: Link for MC Frcition Modifier:

Jbrew

Ford use to say never, just like the E4OD...there wasen't a regimen at first.

But that changed. 60,000 miles is a good number on the rear end. I doubt I'll ever need to change the trans fluid again. The stuff that's in there is just too damn good.

themerc

I pull the cover, wipe everything down, reinstall the cover with a coat of permantex that doesn’t harden, add only Ford friction modifier - that stinks to high Heaven, and pump the gear oil in until it overflows the fill. How often? Annually. At the same time I grease my driveshaft u-joints. The u-joints were changed at 175,000 miles from apparent original sealed bearings. Looked like the gear oil had not been changed in years. Previous owner only did maintenance when something broke. I just don’t like things breaking - so I probably do more than required.