Om651 bluetec oil dilution (oil level increase with diesel)
 

Hello
I have a mercedes. C class with om651 bluetec euro6 c220 170hp form. Problem is that the oil level is increasing. i changed oil 3000km ago and level increased from middle of dipstic right to the max. So right now is at the max. ( measured on flat ground with cold engine overnight)

Car has under 200k km so not a really high mileage car. Car runs good, no smoke, pulls fine, no vibrations or other issues. Exhaust is clean, no errors. Scanned it with a generic diagnose and dpf differential pressure is good, injectors look good.

I drive it dayli, usually 8km in morning and another 8 km in evening ( commuting to work ) and allmost each weekend i make a trip of 100km or more.

Oil seems to be thinner compared to the day i replaced it. I do not feel smell of diesel in it.

I plan in replacing again oil next week after just 3000km and just under 1 month... Original MB 229.51 oil +mahle filter.

Do you guys encountered this before? I recognize that i stopped the car 2 times when dpf was in regen ( felt heat and some burn smell when i stopped in parking lot) but is that enough to increase the oil in such short time? Is not my first car with dpf and never encountered this before...

I need some advice :(
Thanks in advance

Not sure about this particular engine. ..but have experienced something similar where injector seals were the issue allowing fuel to mix with oil. In my case the outcome was catastrophic! !

Is it a possibility that there is water/ coolant in the oil?
Stopping mid regeneration shouldn't be an issue.

I would send oil sample to lab for testing.
Also getting a gauge that will indicate DPF regeneration can be crucial on long run.

If there is either diesel or water in the oil then continuing to drive will be damaging the engine.

Water contamination should be detectable by presence of a whitish froth around the filler cap and obviously a drop in the level of coolant in the tank.

Thanks for replies.

There is no water/coolant. Is definitely diesel fuel.

Stop driving it !!

Tomorrow will replace oil. Will also stop using it. Next week hope that will manage to find a good mechanic to take a look at it.

I just made a video. Injector nr4 seems to have some black dirt. Might be black death i was reading on forums? The copper seals from injector head can solve this problem with oil dilution?

The copper seals from injector head can solve this problem with oil dilution?

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Not necessarily....you may need to look at the seats where the injector seals sit!
They may be pitted and replacing seals may or may not give you a short term solution.

yep, number 4 need more closer examination....

As above either injector is 'pissing' in cylinder (black death case where nozzle holder is cracked may do that, or then faulty injector), or continuous/too frequent DPF regen

Appreciate the reply. Yesterday i replaced the oil. I had around 0.5 liters extra compared to what i have put in(in 3000km and 1 month). Today i drove it 13km. Oil is at level and still clean. Will keep an eye every day to monitor it.

Next week will go to a mechanic to check it as i think that i hear also the timming chain or something else that makes metallic sound. Idk if is real or in my head. The sound can be heard in the video also.

Is strange because i have checked it 1 week ago and all parameters were ok in the diagnostic tool. Dpf ok, injectors ok.

you don't neccessarily see injector true condition by parameters value only... Did you check when last DPF regen was made? Ash content?

I scanned it just with a generig scan tool ( service level) but did not hat last regen or ash contain. Could measure only dpf pressure dif sensor. Was all ok. Next week will scan it with star and come back with a feedback.

All looks good on star. I am starting to think that i measured wrong the oil level. Since replacement i measured it every morning. I have seen that the level is very sensitive to how flat the ground is. If is slightly at angle, level is completely wrong. Also, need to take off dipstick, clean it and on second try i see correct level. Now the oil is at same level as 1st day i replaced it. Took old oil to some mechanics to check it. Feedback is positive. No diesel smell or anything strange with it...

Will keep monitoring it...

Oil dipstick has oring on the top and when it holds- the tube creates thermal vacuum, what sucks the oil higher than it is.
Having car in garage, when I want precision measuring, I pull the dipstick 2 cm up the tube and leave it overnight. The following morning I stick it in and then read.
Not too many orings hold that well, so it is rare issue.
Mechanics know zip about oil testing btw.

+1.
I had the same problem reading oil level. Now Im following kajtek1's recommendations, pulling dip stick out and read oil level next morning.
Way to go.

I have seen that it has an o-ring on dip stick. Usually all cars have it but never encountered this behavior before. Anyway, thanks all for the feedback. Will keep checking it.

And quit drinking vodka before checking your truck *wink*

I have an employee who's from Romania. I'm a vodka drinker, but that SOB can drink me under the table with his mouth stitched shut!

Thanks for advice but is all good :) i usually drink beer, wine or whiskey before checking the oil level. �� vodka is not my thing

Over fuel because of dpf
 

Sorry for my English!
This is known behaviour in some Mazda's engines. There is a additional fuel injection during negative piston cycle. This fuel is needed to help for dpf regeneration.
This additional fuel is catching by the piston rings and going into the oil. Probably the reason is your short city trips. At Mazda the dip stick have a second Max level. When the second Max level is achieved then need to change the oil immediately.

Best Regards,
Dimitar