I am going through a quart every 500 miles. Just driving normally. Any idea what could be causing this and if Mercedes will fix it under warranty or something? This is clearly not normal. It’s 2015 with 75k on it.

 

See if your dealer will start an oil consumption study on your car. This usually consist of them doing an oil change, then you taking it to them when it needs oil added, this builds documentation should you need to get more done later, either through MB USA or the courts. You can also do your own oil study but keep meticulous records.

 

I take it to an independent place who can document everything. Just left there after having it topped off…again. I appreciate the info. Seems odd I would have to “prove” it to get any answers, paying 300 for an oil change I just got done and don’t need. But I guess I will call and see what they say. Maybe we can skip the whole prove it part and do some tests, which is what they are gonna do anyway.

 

Sorry for the dumb question but do you smell oil when you park? As in, is it leaking? Adding oil for that engine every 500 is not normal and something is certainly not proper.

 

If you do find an oil consumption issue remember your cats are down stream $$$$, and probably damaged also, If your car is warranted by MB USA, I'd definitely get them involved.

 

Vehicle was purchased 5 months ago, discuss this with the dealership Service Manager where you purchased: https://mbworld.org/forums/s-class-w...ml#post8558946

 

bigslick, worn valve guides will burn that much oil in 500 miles. When at a stop light & then you accelerate do you notice any exhaust smoke? As asked earlier do you see or smell oil ? Hope you find problem.

 

They thoroughly inspected for any leaks and found none. No oil smell. Car runs fine from what I can tell. The first time it happened I had been driving it hard a few times, thought that might be a reason it burned so much (I was going very fast for a decent amount of times). Technician assured me that had no effect, drove it another 1000 miles making sure just normal driving, and same thing happened at basically same amount of miles….2 quarts burned.

 

To start, you’ll have to try and look at where the oil is disappearing to it’s either leaking or being burned.

Burning:
Like others have mentioned, are you noticing any exhaust smoke aside from cold start vapors? When engine is warmed to operating temp, have a friend give it a few revs or watch the exhaust when you move from a stop.

Leaking:
Take off engine covers, look around with a flashlight for oil spotting or pools, it’s possible the o-ring of the oil filter housing was improperly installed or slipped off during installation (I’ve made this mistake myself during DIY). If you can drop the belly pan check it for fresh pooling, while pan is off place some clean cardboard on ground under engine overnight and see if there are any oil spots. While the engine is warm and running, pop the hood and sniff around, there could be a leak directly onto an exhaust pipe that will instantly vaporize and not be visible below. While the car is cold, open up the coolant reservoir and check for signs of oil in the tank.


Stupid question, do you know if they used the proper oil? Was the tech a MB tech?

 

That was what I was gonna ask same as vincheung . I was told that if we don't use MB specified engine oil the engine could consume more oil .
I'm a Castrol fan but I was told that I should not use Castrol in an M278 engine

 

You have purchased a 7 year old car with 75K miles on it. The dealer and MB are not going to do much of anything to address this as the car is far out of warranty. If you have an aftermarket warranty they will balk at an oil consumption issue unless it is part of a failed component and not just a seal. Leaky seals are typically not covered under the aftermarket warranties as they know this stuff is the first to fail and can be expensive to repair. As others have said, the oil is going somewhere, it is either leaking or being burned. I would suspect a leaky gasket somewhere or a turbo leaking. I have not heard of valve seal failure on these motors and would be surprised if it was that. Most good mechanics can pull all the covers off and find an external leak, internal is going to require some diagnostics including a leak down test on the valves. I would start with the turbos though.

 

Agreed. Unless you have a CPO car, you are expecting far too much of MB.

Also FYI this is not a common issue to the M278. My suspicion would be an external leak which is easy to confirm with a good look at maybe some cardboard.

 

THAT is waaay to much! Are you also saying you let the tech put 1K miles on your car??

 

Take a sample and send it out to Black Stone labs and see where the problem is

https://www.blackstone-labs.com/

Typical Black Stone oil analysis shows the following

https://www.blackstone-labs.com/wp-c...e-combined.pdf

If it looks like a big issue, might consider selling the car and moving on. Few thousand loss now is much better than many thousands later

 

The car was purchased less than 6 months ago from a dealer, take it back and discuss the matter.

 

He might have a recourse if bought at a Mercedes dealership, Indy is a whole new ball game... there's a reason why the PO unloaded the vehicle? Have you ran a carfax to see how many previous owners and sometimes that shows some troubling history too

 

OP’s in Maryland, believe it was purchased in Virginia. Can’t tell if window sticker is MB or not, OP has not clarified. If Independent and not 'As-Is' under Virginia law OP has recourse for repair however, did not realize problem within 30 days therefore vehicle cannot be returned.

 

Another dumb question, is it possible the dipstick is pulled and because of vacuum in the engine the stick is dry and you are adding oil to an engine that does not need it and are overfilling. So the dumb question is are you checking the stick twice before adding oil.

 

May not be relevant to the OP's situation, but I know of a way an engine can consume a lot of oil without leaking or smoke from the tailpipe. Porsche 928s are notorious for oil use and it's from the crankcase ventilation system ... oily vapors are drawn into the intake and then burned along with the gas. My 928 can easily eat a quart in 750 miles when driven hard.

Cars with this problem often get fitted with catch cans to capture this oil and keep it out of the intake.

Again, no reason to think this S-class car has a problem with crankcase ventilation, but it is one way oil can mysteriously disappear.