so here's a question for all you experts out there. I rotated my tires and found on the rear tires those little grease streaks you see when your rear seal is going out. I knew they needed to be replaced just by looking at the tires. but when I rotated my tires the grease was never on the other tires. thinking that my rear diff had ran out of fluid, I added more until I could feel it with my finger like you're supposed to do. I never saw the streaks after that for about 2 years. all the sudden here come the streaks again. but when I went to add more fluid it was full. it streaked for another day and then stopped and it's never done it again. I check the pumpkin on a regular basis but I'm not losing any fluid. its been 7 years. anybody got any clues as to why it would do that?

 

So you think the end seals are leaking? If you have the time it would not be a bad idea to pull the rear ends apart and replace seals, inspect the diff, service the parking brake etc. Actually plan to do that this summer (also replacing the rear brake shields)

But otherwise if there is not strange noise and the diff is full there is now issue.

 

thanks for the info I appreciate the quick answer. I plan on taking it down to my buddys shop and taking apart the front end and rear end. I have a ifs friend and all the knuckles need to be replaced so I figured I would do it all at once.

 

Have you driven your truck off camber? Off roaders frequently encounter this only to discover that there is nothing wrong with the seal at all, just off camber, or parked on the side of a hill in a hilly residential area can do it...

 

Are you sure its not brake fluid? Lot easier to fix a leaking line or caliper. I guess its time to pull the wheels and rotors to be sure which it is. You'll be able to see which right away. The diff fluid has a heavy petroleum order too.
You make no mention of the year make model of the truck. A leaking drum brake wheel cylinder is a possibility too if it has rear drums???

 

its a 93 F 250 XLT 4 wheel drive Camper Special with a 7.5 liter gasser I got it from my dad he bought it brand new and 93