So every time I lift up my car I see this and it annoys the hell out of me.



What can/should I do about this?

Is that just a plain nipple that used to have the stupid candycane thing on it? or one of those cap setups? I had the former on my 2000 MGM, though the candycane must have fallen off before it became mine. I ended up using a long piece of regular PVC hose, put a zip tie over the nipple end, and used more zip ties to route the hose along the parking brake cable down to the bottom of the sway bar. It was fine when I checked it recently.

Thats a huge problem for the 11+ mustangs. Someone makes catch cans specifically for rear axles. The axle is similar so I bet it would fit. Otherwise do as the other poster said and run a piece of tubing to another area to prevent it from getting all over the axle. But be warned without a catch can you will continue to lose differential lube.

+1 on catching the oil makes a mess and stinky, also you need to let moisture (condensation) out but not in. So something is needed not just an open port. Ie the molded OEM hose, and better a vented reservoir

mine has a rubber tube that goes straight up about 6 inches then curves straight down about 2 inches. pretty sure it was there since I got the car. never seen anything leak out of it

I did what I do to my 4x4's axle vents. Long piece of tubing run up as high as possible with a small filter vent on the end. Up high keeps the oil from coming out, it just doesn't make it up that high and keeps water out of the diff's on deep water crossings. The one on my Vic goes up to the top of the fuel tank.

That's the "candycane" thing I was talking about. It seems common for them to get distorted and/or fall off.


It's not clear to me why oil would be coming out at all. I use rust inhibiting oil, so I can't say for sure that mine never leaked without anything on the nipple, but it wasn't obvious that it ever had. The vent is just to allow the air in the diff to expand without building up pressure as it gets warm.

I think a problem might be that people think filling to the fill hole is what's expected, but the manual actually says it should be below the fill hole about 1/4". When I filled mine, the oil came out the fill hole, so I left it to drip. After a half hour, it wasn't showing any sign of slowing, so I sucked some out to ensure it was below the fill hole. The oil is so thick that seeing it drip doesn't necessarily mean there's not much extra in there.

I don't know exactly where the level is supposed to be internally, but I would guess that it's high enough to coat the bottom of the axle tube and get to the wheel bearings but not high enough to contact the axle. Maybe the leakage is just a symptom of the oil level being too high?

Not so much oil itself, but the oil mist suspended in the air. That ring gear spinning a quarter submerged in oil whips a lot of that oil around and one would be surprised how much air is also circulated around by the spinning components in a very confined case. As the heated air in the diff escapes out the vent it is also carrying quite a bit of oil mist with it. Harley wrenches are all to familiar with air/oil separation issues for the same reasons, 2 big spinning flywheels in a very small crankcase though the problem is also exasperated by the 2 big pistons descending down the bores at dam near the same time.

I agree, very little should ever come out, but on my axle, after 16 years and 303,000 miles I have a slight build up.

I put a new one on when I put the new rear in this summer.

What they said. Theres a lot of air moving around in there. Its synonymous with having a motor with breathers. Youll always get oil mist getting pushed out the crankcase. You dont remember how much gear oil you put in?

Was that meant for me? In my case, I bought a jug of oil and used a large condiment bottle to put it in, so things weren't very precise. Oddly, when sticking my finger in the fill hole to check the level, I couldn't tell where the oil level was by feel even when it was dripping from the hole. I'm figuring the best way to verify the fill level is to use the short end of a suitably long hex key.

Oops I thought I read you were the op and now were having problems with diff fluid coming out the axle vent... lol.

Buuuut yea do you have any fluid coming out the axle vent? You should be good with the amount of fluid you used.

Our '01 Merc has the rubber tube with curl on it, I added a zip tie and it's fine. There is no check valve.

Our 2008 Mustang had the cap like pictured above and was leaking a bit at the pinion seal. The car has only 30,xxx now, I noticed the drip when it had only 21,xxx on it. I was gonna change pinion seal but then saw the cap on the vent fitting.

I removed the vent fitting and took into the shop and pried the cap off, it's got a small spring above a disc that lets pressure out but shuts in the lack of pressure. I didn't know how much psi it took to open that check valve though. I decided to leave the cap and spring and valve off and replaced them with a piece of tube leading to a copper tube with a tight U bend in it up above the axle with room for bumps, and then ran a rubber tube into a open frame hole.

There is no more dripping from the pinion seal after a drive. The pinion seal area has remained dry since.

My '77 F150 and my '07 FX4 also vent with a tube. Don't recall what's on the T-birds, they are IRS though .... sure they vent.

I only had a quick look recently to make sure the PVC tube was okay. (I've been concerned that I might need something better.) There was nothing obvious to me to indicate any fouling at the nipple or anything coming out of the end.