Gazwould
MB Enthusiast
Genuine , made by..
How Often Do You Service Your Merc?
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Gazwould
MB Enthusiast
OEM to Mercedes is ?
Gazwould
MB Enthusiast
Highly likely , you pay a premium for the MB yet the product is identical .
I know, I do this because I've done many jobs that are still under MB warranty. In case of issues at least I can say I use genuine original MB parts. I have also some discount so I pay not too much, thanks for the advice anyway. When out of warranty I'll use Mann all day 
Justintyme
Active Member
Justintyme
Active Member
Hi everyone, I have a w245 and a w204 (OM640 and OM651, both diesel). I change the oil accordingly to the trips and usage, number of cold starts, stop&go traffic, dpf-regens, urban or not, etc. I don't exceed 5000 miles. The OM640 (euro5) has serious issues of diluting oil with diesel, so I change it even 3 times a year. I use Fuchs Titan GT1 Pro Flex 23 and Genuine oil and filters. Bye!
So if I understand you right, you have 2 MB cars and the one with the OM640 engine, has serious oil dilution problems. what about the OM651? Is the oil getting diluted in that one as well, or not at all? You drive less than 5'000 Miles per year..is this per car, or a combination of the two. One possible cause is that when only many short journeys are taken, the DPF does not get a complete re-gen. When it gets hot, it starts a re-gen, but because the drive is not long enough to finish it, it stop's. This is repeated many times over and over as the DPF signals it need to re-gen, because it is becoming too "sooty". During the re-gen process, during the exhaust stroke, the injectors pump diesel into the cylinder, which then goes into the DPF to increase the temperature during the "burn" in the re-gen process. If this process is repeated and repeated continually, it will mean an increase of diesel in the cylinders, and thereafter into the sump and engine oil. After the next oil change,,,( or just before it ) ,,take the car out on to the motorway, and select "Manual" then 4th gear, ( if it's automatic, or 4th gear if it's manual transmission) and drive it for about 25-20 Mins with the rev counter between 2'500 and 3'000 RPM. This will enable a complete re-gen to take place. You will need to do this on a regular basis to keep the DPF "clean". Once the DPF is clean, it will stop signalling that it needs a re-gen, and therefore, stop the fuel injection during the exhaust cycle.This is my suggestion and what I do with my W212-OM651, but there may be other suggestions from the forum members on how they cope with this problem. There may be other reason's why the engine oil is being diluted, and with what, but I'm sure that members more experienced than I am will cover the various scenario's.
Hi! Thanks for your answer! I know very well dpf-related issues, I'm not a mechanic but I do a lot of jobs on my cars. I prefer DIY ;-). In reality I posted my witness on this thread not to start a dpf-discussion (I didn't want to obstruct the thread with something not related) but only to give one more report about services intervals on the forum . I can tell you that the 651 doesn't suffer oil dilution. It's quite perfect, oil doesn't move by 1 ml in a year. I do 12-13000 miles per year, but I don't exceed 5000 miles between oil changes generally if I can. The OM640 is known for the issue, even my old OM640 I had was in the same condition. I've already changed the timing chain, so now I keep the oil fresh to not repeat the labour. I've known many people here in Italy with the problem. So, despite I try to make the best usage for a diesel car (oil running for long on operating temp etc), it's often not enough. It's a "feature" of first euro 5 engines, unless you do 200 miles per day it'll dilute anyway I think. There are many scientific reviews about diesel oil dilution, above 5% dilution is considered hostile for engine, so I keep it under this threshold.
. I can tell you that the 651 doesn't suffer oil dilution. It's quite perfect, oil doesn't move by 1 ml in a year. I do 12-13000 miles per year, but I don't exceed 5000 miles between oil changes generally if I can. The OM640 is known for the issue, even my old OM640 I had was in the same condition. I've already changed the timing chain, so now I keep the oil fresh to not repeat the labour. I've known many people here in Italy with the problem. So, despite I try to make the best usage for a diesel car (oil running for long on operating temp etc), it's often not enough. It's a "feature" of first euro 5 engines, unless you do 200 miles per day it'll dilute anyway I think. There are many scientific reviews about diesel oil dilution, above 5% dilution is considered hostile for engine, so I keep it under this threshold.
Gazwould
MB Enthusiast
Lol , the infamous orange plastic dipstick tube snap off .
Fair play as I've done 10 dip stick oil extraction services .
So the car as it stands has 2m+ boost ducting missing , no oil in sump and a snapped dip stick tube .
£5 something + from TPS .
Think I'll be driving the Merc tomorrow .
Fair play as I've done 10 dip stick oil extraction services .
So the car as it stands has 2m+ boost ducting missing , no oil in sump and a snapped dip stick tube .
£5 something + from TPS .
Think I'll be driving the Merc tomorrow .
Justintyme
Active Member
Hi! Thanks for your answer! I know very well dpf-related issues, I'm not a mechanic but I do a lot of jobs on my cars. I prefer DIY ;-). In reality I posted my witness on this thread not to start a dpf-discussion (I didn't want to obstruct the thread with something not related) but only to give one more report about services intervals on the forum
I misunderstood the part about the 5'000 miles...I thought that was your driven miles....not the change frequency !!! And in the 640, you do the frequent changes to minimize the time's/ mileage's that the diesel concentration in the oil would be at it's highest level? How is this working out for you? Have you ever been given a satisfactory explanation as to why this happens in the 640 engine's? Or is it just accepted that this is normal behavior for the 640 engine? ( I'm not very familiar with the 640 engine, BTW) As for the 651, how do you drive it? Plenty of long distance driving or short " hop's" ?
Absolutely no problem!
With the 651 I do many trips of 15-20 miles and some rare 500 miles trips. But I saw that even with bad usage (short repeated trips and many cold starts) till now it didn't give issues of oil dilution. But the car is relatively "fresh" (only 85k miles). For the OM640 I check weekly the oil level, when it starts growing I aspirate some of it, but when about 300ml has already gone into the oil I change the oil entirely, because we are at about 5% dilution. No one ever gave me a decent explanation, but some MB technicians told me that engine has the issue. I don't think I'll keep the car for long because of this problem.
Gazwould
MB Enthusiast
Sadly it's the fuel injectors post combustion cycle squirting fuel to get into the exhaust system to super heat the dpf , this both causes cylinder liner bore wash and engine oil dilution .
The dilution is bad as diesel wrecks the oil's properties .
A better system avoids this by having a fuel injector in the exhaust system .
A bit like the sooty egr , a better system takes the inert gasses post dpf thus avoiding abrasive soot particles being sent back into the engine .
Looks like we have Mark 1 technology !
The dilution is bad as diesel wrecks the oil's properties .
A better system avoids this by having a fuel injector in the exhaust system .
A bit like the sooty egr , a better system takes the inert gasses post dpf thus avoiding abrasive soot particles being sent back into the engine .
Looks like we have Mark 1 technology !
Exactly, sadly few cumulative hours of dpf regen are enough to dilute oil to the threshold point. Few long trips (5-6 hours at operating temp) can make evaporate a good percentage of fuel but at a certain point it's not sufficient anymore (this is what reviews report and also what I saw from experience). Have a nice day
Justintyme
Active Member
Exactly, sadly few cumulative hours of dpf regen are enough to dilute oil to the threshold point. Few long trips (5-6 hours at operating temp) can make evaporate a good percentage of fuel but at a certain point it's not sufficient anymore (this is what reviews report and also what I saw from experience). Have a nice day
So if I ( or anyone else ) drive a vehicle which is suffering from diesel contaminated engine oil hard for several hours and 100's Miles, the high temperature will evaporate (some if not all ) the diesel from the engine oil ? That's a very interesting point. Such a drive would also give a complete regen, which seems to be the root cause of the diluted oil.
Yes, diesel evaporates at a certain rate at operating temperature. OM651 if I'm not wrong has an oil op temp of about 100/110 °C, so it's even easier I suppose. Long trips "purify" oil from moisture, contaminants and fuel, but within some limits. After a number of this purifing cycles, the fraction of biofuel of the diesel which can't vaporize remain in the oil inevitably. They also studied how oil would become starting with a very highly diluted oil running a number of cycles at certain rpms/load etc. They found that piston rings and chain were the most affected components due to dilution. This is what I remember
Justintyme
Active Member
This has definitely added to my knowledge of the MB Diesel engine behavior, and in future what I will do after carrying out an oil / filter change, is to do a 20 min drive at 3'000 RPM . and there after, oil level check's minimum 1 per week, plus at least one drive per week minimum 50 Klms..and at a high RPM. Seems like a lot of this problem is owner caused ( excluding your 640 ) just not enough driving. Thanks for your input.
I don't think you have to be so strict about it. It's also a waste of fuel. These things are valid for every diesel the 651 doesn't have so much issues with dpf, unless you do for months and years trips of 5 miles at cold. Just drive it without all these concerns, check oil level to ensure it's ok and you are fine. Thanks to you
the 651 doesn't have so much issues with dpf, unless you do for months and years trips of 5 miles at cold. Just drive it without all these concerns, check oil level to ensure it's ok and you are fine. Thanks to you
If there is an issue with fuel contamination of the oil whether diesel or direct injection petrol then any question about using either an XW30 oil or an XW40 oil must surely must go in favour of the XW40 to allow a little more headroom for the effects of dilution.
Justintyme
Active Member
I don't think you have to be so strict about it. It's also a waste of fuel. These things are valid for every diesel
A very simple solution to all these regen issues would be a warning light on the dash indicating when a regen is taking place.......because these dilution issues are brought about when there is repeated attempts to regenerate, and this happens when one starts, but does not finish, and it will keep attempting to regenerate. A kind of vicious circle if you like. But each attempt is injecting raw diesel under pressure into the cylinder, hence the dilution of the engine oil.
