2004 4x4 --- there is gear oil leaking from the front axel housing, at the passenger side end, between the end of the axel housing and the start of the half axel. Seal gone I think. I though it was slow enough that I could just squirt some gear oil (synthetic 75-140 is what the dealer recomends, though 2004 manual says 75-90) every oil change, but this time, it seemed VERY low, about an inch below the fill hole (supposed to be .38"). And took a pint to get up to correct level. I am thinking it may be time to fix it right. First, I need to double check the vent. If that is plugged it could be forcing oil out when it gets warm. But I doubt... Assuming that the oil seal needs replaced, the axel needs pulled. Shop manual shows a slide hammer, but apparently, Ford used some sort of "circlip" which holds the axel in place. Manual says to replace these when re-installing the axels. Unfortunately, the manual does not say exactly whether the old circlip comes out with the axel, or gets left behind to be removed later in the tear down -- the manual just describes a complete tear down, which of course I don't need. If figure if I have to completely tear down the differential, then this is best left for a stealership. Anyone have experience replaceing the seals up front?