Diff oil...too much of a good thing

Apr 22, 2005
Northern NJ
So this weekend I drained the front diff and filled it with M1 75 w 90. When I unsrewed the fill plug oil started pouring out immediately. I was on the street, and figured the truck was on a bit of a decline. I put in about 2.5 US quarts (the FSM calls for 2.8 for diff's w/ lockers). After driving around for a day I felt uneasy about not putting in more. This time I parked the truck in a buddies garage, and I planned on filling it until some oil poured out. The diff ate another quart of oil without any running out of the fill hole! I'm wondering if there's a seal inside or something that has gone bad, thus draining the diff oil into some insatiable sink. I pulled that explanation out of my a$$ b/c I'm not familiar with the inner workings of the axle. ANyone have a similar experience? While I had a roof over my head I swapped out the PCV valve...that grommet sucks to change, I went straight to step #6 after that.

Nov 21, 2004
Well if you are loosing oil out of the diff it would probably have to end up coming out by your hub, CV what have you............there should be grease here, but not oil
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