The last two days I've been smelling differential oil while driving home with the windows down. I looked under the car and saw heavy seepage on my diff cover. I figured "great...now I have to rip the **** thing off and reseal it" but when I got under the car to wipe it down, to my surprise it wasn't the diff cover because the whole passenger side of the axle was coated in a heavy layer of the stuff. It looks like the axle overflow valve up-chucked (technical term) for some reason. Does anyone know why it would do this? I haven't changed the fluid on my diff for about 15,000 miles so if it were overfilled, you'd think it would have overflowed sooner.

My only guess is that last week I went on a road trip, got pissed at traffic and hit 100+ MPH (probably 120 peak) and took a couple fun curves at speed. Maybe it churned up the oil

 

bump

 

Easy fix: http://www.shelbystore.com/product-p/8r3v-4022-kr.htm

 

Even easier fix: Ford has a TSB (10-3-7) that replaces the diff vent with an improved version that addresses this problem.