1994 buick roadmaster, oil leaking out of right rear axle, checked brake fluid is full, could it be differential oil leak @ end of axle??

Place a piece of white paper/cardboard on the ground below where the leak is coming from soon after the engine is turned off. This should help you locate where exactly the oil is dripping from, and should help identify what is leaking. If the oil is black/brown/gold, it's probably engine oil. If it's reddish/brown, it's probably transmission fluid. If it's clear, it may be brake fluid or power steering fluid (from the rack/pinion). Check the fluid levels for whatever you determine it may be. If it's engine oil, you may have leaking valve cover gaskets or a leaking rear seal on the engine. If it's transmission fluid, you may have bad transmission cooler lines or leaking from axle seals. Check the master cylinder and brake lines if it's brake fluid, and check the rack/pinion if it's power steering fluid.

The only things I can think of at the moment, is either brake fluid or rear end fluid.

if your talking about the rear brakes its probably the differential axle seal that is leaking differential oil out of the rear end onto the brake shoes. you will have to pull the rear axle to replace the seal and clean the rear brakes/area with brake cleaner or replace the rear brakes if they are too soaked with brake fluid.

This is different. In a perfect world, you would run the truck on a dynamometer, get it up to 55 MPH and look under the truck. The fluid is going somewhere.
There is a vent tube on most axles. Follow the tube to find its' end and see if the fluid is traveling away from where you had expected a leak. Check your axle shafts under the rear rotors to see if the Emergency brake drum is oil coated.
Another way to think about this is the original failure. The pinion seal. The seal contacts the rotating flange. If you have a wobble in the driveshaft, (balance issues, U-joints) then the rotating flange can wobble. If you have a bad pinion bearing or carrier bearing, it can work to make the spline gear wobble.
So I am suggesting that the leaking Pinion seal was caused by something and the seal was a casualty of an undetermined cause.
You should be able to add an Ultra-violet dye to the axle fluid to find your leak. Even if it is running from the same place, the current leak will be showing the UV dye.
Please rate my info.

Jack the vehicle up and check the brake caliper. If it isn't a seal on the caliper make sure you check the shock absorber to make sure that isn't leaking. If that is not leaking it is most likely the axle seal. Unless Ford has changed the design of that your going to have to open the rear differential, remove the retaining clip for that axle and extract it from the Axle housing. The seal is typically pressed on so it is going to be a pain to remove the old seal then press the new seal in place and re-assemble the rear end. Make sure you fill the differential with the proper fluid or you'll burn the rear end out. When your checking the caliper make sure you check the brake line for breaks and the bleed valve to make sure that is in place and not leaking.

yes theres a seal from the axle shaft, but theres a also your brake cylinders. to find that you need to remove the tire and check the brakes or check the brake fluid reservoir for low fluid. either way you need to remove the tire. if its your axle seal then the pin theres pins on the actual differential to remove the axle shaft. a little more complicated. check the axle shaft to wear from the seal and bearings. also check the diffrential for a good level or you will loose the diffrential if you keep on running it. the level check is on a plug like half way that ususally removed by hand or a ratchet then stick your finger and if you dont feel it put oil on,. the proper oil level is when you can feel the oil with out sticking in a rod or stick in there. hope this helps

hi , make sure its not the brake cyl. leaking, if its rear seal leaking remove brake shoes, then remove axle bolts, replace new seal, then check rear end fluid

as long as it doesn't get on the brakes you're ok

Nope they are right.

This is a common problem on lifted Tundras



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You are correct, it's not brake fluid. Check the level in your rear axle, it sounds like you have bad seals in the axles allowing the rear differential gear oil to leak inside the brake drums.
This is a heavy weight oil, 80 or 90 weight. This leakage will ruin your brake pads, and if enough leaks out, your rear differential will blow. The seals aren't expensive, but it's a lot of labor to pull everything apart to get at the seals, plus new rear brakes. My Ford ( and I'm sure your GMC) require removal of the rear axles to change the seals. Good Luck! countrycurt0