Smoke/oil smell from rear wheel well

My 2012 Ram 2500 will the 5.7 Hemi occasionally has a burning oil smell and a small amount of smoke coming from the rear drivers side wheel well after a long trip pulling my camper. It doesn't do it when I drive it unloaded or on short trips, but it does do it on longer hauls like today's 3 hr trip. I don't see any evidence of my rear end leaking oil through the seal and the brakes look fine. Anyone have a clue what it could be? Oil level looks fine too on the dipstick. I'm not aware of anything on the drivers side rear end that could be doing it.

have you checked the bearing for looseness/wear? Doesn't take much gear lube to smoke on a hot bearing.

Do you use the parking brake? My 04 would not release and cooked the axle seal. No visible oil leaking. Just a light coating on parking brake shoes.

I jacked the truck up last night and tried to wiggle the wheel, it didn't move so hopefully the hearing is good. I do use the parking brake when towing the camper, I need to take the wheel off and take a look but might have to wait until I get home since I'm at the campground this weekend. It seems like it isn't actually coming from the wheel itself but from the wheel well area. Noticed it while sitting idling checking in to the campground yesterday, it was a constant but small amount of what looked and smelled like burning oil.

check the rear differential vent tube, sometimes they are routed up on the frame in that area. All the people I know with those trucks that tow a good size camper, have the extra capacity differential cover on them.the fluid gets cooked pretty fast when towing.

Just looked under there, sure enough the vent tube from the rear axle is right there. Thanks! Took the plug out of the differential cover and stuck my pinkie in and couldn't feel any oil. I'm assuming it should leak a bit out of the fill hole when it's full? If so I need to get some more oil in there.

...And SOON!
Maybe it got hot enough to boil and vapors oozed out?

I ended up putting a little less than half a quart in, brought it up to where I could touch it with my pinky. Oil looks prettty black so I'm going to change it when I change the engine oil here soon. It's only done it twice, both times after going through stop and go traffic on the interstate in Omaha, so I'm assuming it's the stop and go that's heating up the rear end. I've taken other long trips and never had it happen but they were all nice steady speeds.

it would be in your best interest to pull the cover & axles and do an inspection as well as refill it with fresh fluid. Higher capacity covers are not that expensive and usually have fill/drain ports on them for easy servicing.

get yourself a lube locker gasket from Amazon for your application too.


I also like to put a few 1/2" round by 1/8" thick Neodymium Magnets inside the case to catch metal flakes and act as filters.

Is the factory gasket reusable, and the lube locker an upgrade or do I need to get a gasket before I drop the cover? Looks like increased capacity diff covers are $2-300 so I need to do some research there. Truck has 75k on it and would like to eliminate any costly repairs.

more than likely there is no factory gasket, RTV is the go-to for differential covers. A Lube Locker gasket allows you to skip the RTV all together and reuse it.

Some aftermarket differential covers have a machined recess for an O-Ring gasket, so don't buy a lube locker gasket until AFTER you choose a diff cover depending on whether or not you'll need it.


it's also important to get the right mix of limited slip additive to gear oil when you do change it, not enough and it'll chatter around corners, too much and the clutch plates will slip too easily. For that reason I use the Royal Purple gear oil, already formulated and has done good for me.

Sounds good, I run Royal Purple in the engine so I might as well put it in the rear end as well. Thanks!