Carcheologist

I'm still chasing high oil consumption on our ML350. It's using a quart about every 300 miles. I usually use Mobil 1 0W30 or 5W30 and change the oil around 5000 miles. We bought the ML 5 years ago with 138k miles.

Does anybody have any other suggestions on things to check or try?

The PCV valve was replaced by me last year, then again during the emissions modification apparently. Either way it's newer and the latest updated version.

Here's my plan:

Remove the splash shields underneath and watch for leaks. I pulled them yesterday and they seem pretty dry. Also had a bunch of seed husks thanks to our local rodents.
Change air filters (I changed them last year 6000 miles ago)
Oil change (it's due)
Install ProVent 200 oil catch can to see how much oil is getting past the PCV valve
Try some sort of Motor Medic, MMO, etc to see if I can remove the carbon from the rings

My theory is that I have stuck rings, or worn cylinders. Last year when parts were backordered it was running the regen cycle very frequently, and I'm wondering if it washed too much oil off the cylinder walls. I sent the oil to Blackstone for analysis and it came back with high fuel levels in the oil.

Are there any engine treatments anybody recommends to try to unstick the rings? I'm generally wary of snake oils, but figure it's worth a try.

Should I get a compression check?

Any other ideas?

We really like the ML, it meets all our current needs, but if I can't fix this I will probably trade it in and get a gas version or a minivan.

Thanks!
Ian
Portland, OR

John CC

Liqui Moly Pro-Line Engine Flush. It's snake oil, but it helped on a gas engine. Two 500ml cans in an 8 quart sump right before an oil change.

A quart in 300 miles is a lot of oil. I doubt it's leaking; you'd have a lake of oil under the car. Check the compressor wheel of the turbo for oil leakage.

Chrome988

I had this EXACT same issue with my R350 bluetec.
I did the bluetec recall which changed tons of parts including the pcv valve but no avail.
Mercedes dealer wanted to charge 600 just to diagnose excess oil consumption, why pay to find out about an issue I already know about?
I did hours of research on this issue and I have a thread on mbworld about this exact problem on the R class forum.
My research suggests it is almost certainly the piston rings. There is no blue smoke coming out our exhaust pipes due to the dpf and SCR (adblue system).
Sell the car, it's not worth chasing.
I sold my r class very cheaply because I was so irritated by this issue. If you are madly in love with it, put rotella t6 heavy 15w40 oil, maybe less oil will slide past the rings if its heavier.

John CC

I'm not sure what MB oil spec your engine is supposed to have, but if you want to try an HD Diesel oil, try Chevron Delo 400 XLE 15W-40. At least it meets the MB 228.51 spec.

T6 meets MB spec 228.31. If that's OK for your engine then it's a good oil, readily available and reasonably priced. (Looks like you need 228.51, unless you don't have a DPF)

Quint22

Get a compression check, also I am not sure how the jelling issue presents itself before seizing the engine but something else to look at.

If the rings are blowing by enough to burn thru a quart every 300miles it should be blowing by when you remove the oil filler cap. Regardless changing oils to a thicker oil if you will wont do squat to combat the oil loss. Change oil types if you want (I have no qualms about that) but if you are going to fix the vehicle take it to a independent and have it checked out.

Also if the oil is actually burning off that quick your DPF is gonna get clogged up much quicker than it should. If its going down the tailpipe I am surprised it hasnt already. Do you have a monitor that can track regens?

tjts1

If "MB spec" oil was so brilliant we wouldn't have so many om642s with stuck piston rings burning quarts of oil every few hundred miles. MB is more concerned about protecting the DPF than the engine.

John CC

Yes, we know.

Carcheologist

Thanks for all the tips.

I did an oil change a few weeks ago, using Costco diesel 15W-50 and also added some Seafoam to the oil per the instructions (I had some on hand). We drove it about 300 miles, and it still burned about a quart of oil over that time. So I did another oil change with the recommended Mobil 1 5W-30 ESP, and have about 90 miles on that so far. We luckily don't drive the car that much these days since we got a little electric Fiat 500e last year. But the heavier oil didn't seem to significantly slow the oil loss.

So I was thinking I'd try to put about 1000 miles on this oil then try the Liquimoly engine flush treatment.

I also installed a ProVent 200. After 300 miles it hadn't collected any measurable oil, but did collect some water. Interesting.

That has me wondering if the turbo is leaking? Or possibly the oil is getting past the rings and burning so not showing up in the PCV system.

I have also been considering putting something straight into the cylinders and letting it soak to try to free up the rings. Also putting a scope in there to see if there is any crosshatching on the walls. Is the injector the easiest route to getting in to the cylinder, or the glow plug? Neither sounds like fun.

I will keep updating as I find more. I'm also researching new cars, but don't want to spend the cash at the moment so hoping to limp this along for a bit longer.

(Edit, 300 miles, not 30. Updated above)

tjts1

The 0w30 and 5w30 229.whatever oil killed your om642. The provent in the PCV will not show appreciable oil acumulation because your compression rings are fine. Only the 3rd ring down oil control ring fails. Your DPF is collecting all the smoke. If you remove the DPF you'll fumigate the neighborhood.

Sadly MB decided to prescribe oil which is good for your DPF, not so great for your oil control rings. I've seen the same story over and over. There is no solution besides replacing the rings. 229.51/52 oil kills OM642s.

kajtek1

I have several lab tests proving otherwise.
Take you poison somewhere else.

tjts1

Oh good! I'm sure your "lab tests" are going be very comforting to the OP who is burning a quart of oil every 300 miles.

🙄

Michelina

Hi,

Was this right after the "Free Install Field Measure to Update Emission Control?"

kajtek1

I guess your coffle-grinds judgement that it is 229.52 creating it is much better?

John CC

If you believe it was the oil, or you have no other options, read this.

Note the reference to a special oil filter. If you decide to try this I would recommend one or two filter changes during a 5000 mile OCI.

Michelina

mine is doing the same thing. They are at fault and I believe they know it. Keep at it!! I have spoken to others who had the same recall who are experiencing the same thing. It is not us!

Michelina

yes!!! They know it!! But it is too expensive to replace the rings so Mercedes is waiting to see how many owners will give in and get rid of their vehicles rather than fight them on it. I love my truck and am not going to let them get away with this.

Michelina

Mercedes knows what is wrong!! They are just waiting to see what the most inexpensive way they can find to get out of it. Don’t sell!!

Carcheologist

It started right before the AEM update, when the DPF regen cycle was running all the time.

Carcheologist

So I have an update.

We have just over 1000 miles on the ML350 since my last post.

I'm running the usual Mobile One 5W30 ESP that meets the MB 229.52 spec. I have been waiting for the car to tell me when the oil level is low, which I believe is when it's down about 2 quarts. I will double check the dipstick when it happens.

But I checked it yesterday after it hit 1000 miles and the oil level is right in the middle of the dipstick, so down about 1 quart.

I haven't had a chance to check the oil catch can yet, but plan to when it dries out for a couple hours.

So again I ran some cheap 15W40 diesel oil for 300 miles with 8-9 oz of Seafoam for 300 miles. Then changed the oil and went back to the usual Mobil One ESP. I also added a Provent Catch can at the same time.

I have never seen the oil as clean as it was after the second oil change. It didn't turn black immediately like usual, making it harder to gauge the level when refilling. But even if I overfilled it slightly it's well past 500 miles per quart.

I'm obviously keeping an eye on the oil consumption, but if it continues like this I can easily justify keeping the ML for a while longer. I'm happy to add a quart of oil every 1000 miles. Even 500 miles given how little we drive it. But 300 miles was definitely concerning.

Carcheologist

That's interesting, thanks! My Seafoam treatment was trying to do the same thing. So far it seems to have helped, and I plan to try it again. I'm thinking of changing the oil at 3000 miles and doing another 300 mile treatment with Seafoam.

But I will also keep an eye out for that Valvoline oil, at the moment it seems to be unobtainium.

John CC

Try a Cummins repair shop.
(Link to wrong product removed.)

olesouthernboy

The produce you have the link to is not the correct product. The product that cleans up the carboned rings is Premium Blue RESTORE. It is about $80/gal. A friend of mine owns a heavy diesel operation and gets it for me from a local truck dealership (cummins dealer i think). I have used it in my 2013 GL350 (230K miles) as a preventative. I didn’t expect any changes since my GL only uses about 1/2 a quart in 5,000 miles however, I ran it in my wife’s Lexus LS460 and it definitely cleaned something. When i drained the oil is was freaking orange. My guess is that the engine had quite a bit of varnish that was removed. Her car also doesn’t have a consumption issue but I’m all about preventative maintenance and this product seems to work well, time will tell. I have read a bunch of information from various sources about the premium blue RESTORE product and they all really positive on the results. I plan on using it in both cars every 25-30K.

John CC

You're right...

There's another product, Valvoline Restore and Protect that's supposed to have similar effects. Might be worth considering.

Carcheologist

I saw that when I was looking for the Blue Restore product, which looks like it might be discontinued. I might try that, or do another Seafoam treatment before my next oil change.

John CC

I used Liqui-moly Pro-Line Engine Flush, 2 x 500ml cans in a Volvo (gas) with a 7 quart sump. I went from about a quart in 300 miles to about a quart in 1000 miles over a couple thousand miles, at which point I sold the car. I would probably have tried one more treatment before the next oil change.

You throw it in right before the oil change and let it run for half an hour or so, then drain.