burning oil after oil change

[catmandoo]

this is the weirdest thing i have ever experienced and i've just noticed it the last 4 or 5 times i've changed the oil.for about the first 2 days after changing the oil i can smell the exhaust and it smells like burning oil,after a couple days it goes away.at first i thought i was getting oil on the crossover but the last 2 times i really looked and none to be found,this truck is spotless underneath to the point i wouldn't be afraid to eat off of it.there is no oil leaking whatso ever heck the oil pan is dryer than the sahara desert,this has to be the cleanest engine i've ever had but this oil smell is getting me,has anybody else noticed this.when this first started or i should say i first noticed it i was at a stoplite and had the windows down and i thought it was the car next to me ,but then i stopped on a gravel road intersection to look for something in the back and i could smell burning oil so it pretty much narrowed it down to where it was coming from (me)since then after every oil change it stinks of burning oil for a day or two then it goes away.

[Scooby]

I have noticed a hot oil smell on diesels before, right after an oil change. It doesnt smell burned, just like new oil that is hot, and vaporizing a little. I noticed it on some big trucks I have worked on, a 3 cyl diesel forklift I have at home, and on some yard equipment also. All diesels. I think it may have something to do with the additive package added to the oil. Fresh oil will have high amounts of the additives that may give off an odor when first getting warmed up. That is what I have always thought, and that maybe it is coming out the breather on engines that are vented to atmospheric. The big trucks I have noticed it on were Cummins powered, and had a breather tube on the right side of the block.

As for the BURNED oil smell, maybe the new oil cleans the seals at the turbo, and a little oil is getting sucked in. Or,,, the breather could be allowing the odor, or a little vapor through into the inlet side of the turbo, and then it gets burned.
Just a guess.

Rick

[BuffaloGuy]

I've always attributed it to the oil that gets on the front drive line when changing the filter. It gets right on the u-joint. Then when moving it probably flings up on the cross over pipe.
Ken

[Polar Diesel]

Every time I cange my oil, the exhaust smells like new oil for about 500 miles. Nothing visible just smell. I think it's the turbo seals leaking before oil pressure comes up on a spinning turbo. That's all i can figure, it doesen't burn it.

[David Brady]

I don't know about smell, I'll have to check that but I have noticed a leak at the rear main after I change my oil, just a dribble that goes away with warm up. It seems to be related to how cool the truck is when I change the oil, the cooler the worse the leak. Is this common? Other than at the oil change mine doesn't leak.

[DmaxMaverick]

That smell is normal. Depending on oil brand, it could be better, or worse. The vehicles with CDR (closed circuit) aren't as bad as those with a crankcase vent to atmosphere. Dripping oil onto the driveline, only to be slung onto the crossover would definitely cause a heavy smell. The front driveline should not be turning, unless in 4wd.

Rotella is about the worse, Delo isn't as bad. The full synthetics (Amsoil, Mobil 1, Redline, NOT Rotella, Castrol, LE) are not as bad as the dino's. 15w-40's seem to be worse than the other viscocities.

It is the additive package that causes it. The smell will usually settle down after about 500 miles, depending on driving habits.

[Polar Diesel]

But in my case, i'm pretty sure it's turbo related. My 6.2 never did it and i use the same rotalla.

[DmaxMaverick]

None of my 6.2's (or '92 6.5 N/A) did it either. The crankcase venting is very different, as are the pressures/vacuums, compared to turbo'd or later models.

Yes. I agree it can be turbo related, but not due to a leak (unplanned, anyway). It would take a bad leak, one you'd notice, to cause the smell, and it probably wouldn't go away after 500 miles.

[Polar Diesel]

well i was thinking after 500 miles the soot would soak up the oil in the down pipe. Also I think it takes oils pressure to keep the shaft in line in the turbo? Therefore with no pressure it may sag and cause a small amount of oil to seep by the seals. Just a Therory though.

[Polar Diesel]

oh i should add- 200,000 miles are on this unit.

[jlog]

a lot of the time when you change oil the drain down period is not long enough. If you fill with the reccommended quantity ie 7 qts you end up over filling the crank case by about 3/4 to 1 qt. the eccess gets blown out. this was explained in a gmc bulletin that warned users not to check the oil immediatly when pulling in for a fuel fill.

john

[Polar Diesel]

Hmm? i always put 2 gallons in because i buy rotella by the gallon. but i did this with the 6.2 and it was fine. either way, 7 or 8 quarts, don't matter. You would have to way over fill so the throws of the crank hit the oil for it to cause a problem, i would think.

[catmandoo]

as i said mine is spotless underneath and a 2 wheel drive so the oil and oil from the filter drop straight down,as someone said 6.2 n/a and 6.5 n/a didn't do this and mine didn't either until i put my banks turbo on it and then i really haven't noticed it til the last couple of months.i changed my oil last thursday and it was a strong smell and been getting less ever since and today it's still there but if i drove gassers all day i probably wouldn't notice it.when i fill mine with oil i fill the filter before i put it on and then i only put 6 qts in it and start it and run it for 30 seconds or so and shut it off and let it set for a couple of minutes then check the level and add what it needs.

[Polar Diesel]

does the smell come out the tail pipe, or the engine compartment? Mine is in the exhaust gas.

[David Brady]

I just changed my oil over the week end and stopped to sniff the pipe (I made sure no one was looking)and it really did smell like a little oil burn! I use the amsoil 15-40 synthetic. I've never smelled this before and it's not in the engine compartment. Pretty wild!

[catmandoo]

mines out the pipe and it usually lasts like 600 or so miles.weirdest dang thing,and i never had this problem when it was n/a.

[DmaxMaverick]

Of course you are going to smell it at the tail pipe at times. That doesn't mean you are "burning" oil.

Soon after you change the oil, it starts to "vapor" off some of the additives and the oil itself. The vapor has to get out of the engine somehow, either by a vent open to atmosphere, or some type of capturing system.

In our case with the 6.2L and 6.5L engines, we have a CDR. The purpose of the CDR is to maintain a specific pressure in the crankcase. It vents excess pressure into the intake, which later becomes exhaust.

A turbocharged engine exposes engine oil to higher sustained tempuratures and pressures than in a N/A engine. This causes a more rapid vaporization of the oil. This results in a more pronounced odor. Same oil. Same odor. Just more of it, more often. Also another reason for more frequent oil changes needed if you have a turbo, or run it harder than "normal".

[diesel joe]

I have found that certain oils have slightly different additive packages and this might be what's causing the smell. It's not burning oil, but a reaction with the seals, specifically the rear main seal. I owned a Grand Am that stunk something terrible for the first 500 miles after an oil change, when stopping at a stop sign or parking in a garage. GM has a bulletin addressing this issue by replacing it with a new improved seal. There is no bulletin from GM for the 6.5. Don't let this become a big concern, because it dosen't hurt anything but your nose.