Oil report question, Fuel in oil, e320 Bluetec

[GreeshaK]

Hello all.
Was finally allowed to register, have a few questions.
Changed the oil on our 07 e320 bluetec at 101k miles.
Done oil changes at 5k its entire life, as well as all other recommended services, at our local independent.

Always using the correct oil, mobil 1 oil.

Comments:
We found nice low wear on this first sample form your e320- maybe a bit too low. Our universal averages show typical wear from this type of engine after 6200 miles of oil use. Your oil run wasnt quite as long, so lower wear is to be expected but your wear is far enough below average that its possible the 4.5% fuel may have diluted the sample. It definitely brought the viscosity down into the 5w20 range. The fuel doesn't seem to be causing extra wear, but if the oil level is rising on the dipstick, you may have a fuel system issue. The TBN was okay at 3.7

Doing searches around other forums, people claim that GM trucks allow up to 5% as normal in their diesel vehicles.


Thats GM, not mercedes, nothing against GM, but different companies have different allowed values.

Any input?

 

[GreeshaK]

Sorry, forgot to post these

 

[Garak]

Thanks for the report. I certainly don't have any information on your application, but it's certainly interesting information to note. Which M1 was this, 0w-40? Talk about some shear, though!

 

[GreeshaK]

Originally Posted By: Garak
Which M1 was this, 0w-40?

5w-40

Originally Posted By: Garak
Talk about some shear, though!


New to oil talk, what does this mean?

I had initially though it could be bad rings, but at 100k not likely.


Asked around on a mercedes forum:
There is nothing wrong with your engine. Its caused by cost-cutting engine design by Mercedes and your driving style.
Your engine has an exhaust filter, in order to burn the soot out of it the engine is programmed to dump raw fuel into the exhaust to raise the exhaust temperature. Naturally, a lot of that fuel makes its way past the cylinder rings and into the oil.
Its the same problem all modern diesel engines have if they don't use an external injector/burner in the exhaust system. Ford, GM and Dodge allow up to 5% fuel contamination in the engine oil because of this.
Your driving style is a major influence on it. City driving, idling, stop and go traffic, short trips and/or driving gingerly will increase the need to actively regenerate the filter (dump fuel into the exhaust). A highway drive above 55mph for longer than 20 miles will regenerate the filter passively (natural heat from the exhaust).
The only possible way to completely prevent the problem is to remove the DPF and the ECM programming that checks for it. This will also give you a significant increase in fuel economy and engine life.

However, this makes no sense to me, as I am yet to have the particulate filter regeneration cycle go off in the car, not that I know of.

I changed the oil most recently at 4k miles, will send the sample in tomorrow.

 

[JHZR2]

There is lots of fear related to fuel dilution. Diesel, having more high boilers (less volatile, heavier chemical compounds), may be slightly more similar to the light end of motor oil, making it slightly more acceptable to have in the oil as a diluent.

Specifics of how fuel (gasoline/diesel) destroys a lube oil (besides bringing viscosity down, which may not be an issue, and lowering flashpoint, which again may not be an issue). Certainly it is not good, but just how bad it really is, I have not personally seen well-quantified.

 

[m37charlie]

Which Mobil 1 5W40?? Formula M, ESP Formula M or what? The TBN may be "OK" at 3.7 but unless it started at a low level like 6.4 it is pretty low for a mere 5000 miles.

Charlie

 

[GreeshaK]

Originally Posted By: m37charlie
Which Mobil 1 5W40?? Formula M, ESP Formula M or what? The TBN may be "OK" at 3.7 but unless it started at a low level like 6.4 it is pretty low for a mere 5000 miles.

Charlie


ESP Formula M according the the shop. I asked several times, and they put the correct one in.

 

[BMWTurboDzl]

Eh.. from what I've read the amount of fuel sent down to the DPF is minimal. I wonder if a leaky injector is the culprit. What do you think Charlie?

 

[GreeshaK]

Originally Posted By: BMWTurboDzl
Eh.. from what I've read the amount of fuel sent down to the DPF is minimal. I wonder if a leaky injector is the culprit. What do you think Charlie?


what I dont understand is how fuel sent to part of the exhaust system would end up in the oil.

I also thought that leaky injectors make a very distinct sound when

 

[m37charlie]

Originally Posted By: BMWTurboDzl
Eh.. from what I've read the amount of fuel sent down to the DPF is minimal. I wonder if a leaky injector is the culprit. What do you think Charlie?


A leaky injector would be responsible for some black smoke at least before the oxi-cat heats up. I don't know for sure how much fuel is "post-injected" during active regeneration cycles but I suspect it is a fair amount judging from the fuel economy penalty. I dearly wish someone would make EGR/DPF delete kits for BMW and MB diesel cars.
As far as the TBN issue, ESP Formula M is a low starting TBN oil, I think in the 6.2-7.5 range. 3.7 isn't bad considering my "best guess" of 6.4 for starting. They don't publish it because it is so embarrassing.

Charlie

 

[BMWTurboDzl]

Originally Posted By: m37charlie
Originally Posted By: BMWTurboDzl
Eh.. from what I've read the amount of fuel sent down to the DPF is minimal. I wonder if a leaky injector is the culprit. What do you think Charlie?


A leaky injector would be responsible for some black smoke at least before the oxi-cat heats up. I don't know for sure how much fuel is "post-injected" during active regeneration cycles but I suspect it is a fair amount judging from the fuel economy penalty. I dearly wish someone would make EGR/DPF delete kits for BMW and MB diesel cars.
As far as the TBN issue, ESP Formula M is a low starting TBN oil, I think in the 6.2-7.5 range. 3.7 isn't bad considering my "best guess" of 6.4 for starting. They don't publish it because it is so embarrassing.

Charlie
IIRC it's ~1% hit to FE. Do a search on the injection system (i cant from phone). The literature mentioned something about a single pulse of fuel being sent down the exhaust during Regen.

 

[GreeshaK]

Originally Posted By: m37charlie
Originally Posted By: BMWTurboDzl
Eh.. from what I've read the amount of fuel sent down to the DPF is minimal. I wonder if a leaky injector is the culprit. What do you think Charlie?


A leaky injector would be responsible for some black smoke at least before the oxi-cat heats up. I don't know for sure how much fuel is "post-injected" during active regeneration cycles but I suspect it is a fair amount judging from the fuel economy penalty. I dearly wish someone would make EGR/DPF delete kits for BMW and MB diesel cars.
As far as the TBN issue, ESP Formula M is a low starting TBN oil, I think in the 6.2-7.5 range. 3.7 isn't bad considering my "best guess" of 6.4 for starting. They don't publish it because it is so embarrassing.

Charlie


From what I have read on forums, people have cut it out, and reprogramed the computer, thats that hard part.

Regarding the TBN, if they had filled it with regular mobil 1 synthetic 5w40, would the low tbn be alarming?

 

[GreeshaK]

Originally Posted By: BMWTurboDzl
Originally Posted By: m37charlie
Originally Posted By: BMWTurboDzl
Eh.. from what I've read the amount of fuel sent down to the DPF is minimal. I wonder if a leaky injector is the culprit. What do you think Charlie?


A leaky injector would be responsible for some black smoke at least before the oxi-cat heats up. I don't know for sure how much fuel is "post-injected" during active regeneration cycles but I suspect it is a fair amount judging from the fuel economy penalty. I dearly wish someone would make EGR/DPF delete kits for BMW and MB diesel cars.
As far as the TBN issue, ESP Formula M is a low starting TBN oil, I think in the 6.2-7.5 range. 3.7 isn't bad considering my "best guess" of 6.4 for starting. They don't publish it because it is so embarrassing.

Charlie
IIRC it's ~1% hit to FE. Do a search on the injection system (i cant from phone). The literature mentioned something about a single pulse of fuel being sent down the exhaust during Regen.


If you get a chance, please post the article you were referring to.
The poor fuel economy has to be linked to something in the exhaust system, because what else would explain mercedes designing a new engine and having worse economy. Honestly, with the amount of vehicles mercedes is dumping these engines into, the v6 has to be a solid engine.

You are both bmw guys, do you get a light that comes one when your dpf is regenerating? I have seen press photos of dpf lights in other mercedes vehicles, but have yet to see it come on in ours.

Also, maybe I missed something, but some articles say that mercedes adjusts engine permitters, and does not directly inject the fuel into the system. You guys say it sprays it rite in there. That still does not explain how it gets into the oil?

 

[m37charlie]

There are 2 methods of "post injection" of fuel in order to light off the soot in the DPF.
The cheaper (initially) way is to have the regular in-cylinder fuel injector squirt raw fuel into the cylinder in the exhaust stroke. This can cause fuel buildup in the oil.
The better way is a "7th injector" downstream of the engine in order to inject fuel into the exhaust manifold or even post-turbo. This obviously cannot cause fuel contamination of the oil.
Regarding the TBN question, it all depends on the initial TBN of the oil. Mobil does not make hardly any Euro-engine qualified Mobil 1s in 5W40s but there are about 3 at least Delvac 1 5W40s with TBNs ranging from 10.1 to 16. Clearly in the case of any of those a drop to 3.7 in 5k miles would be mysterious. Again, considering that ESP Formula M likely has an initial TBN of 6.4 measured by the D2896 protocol, 3.7 measured by D4739 (yields lower numbers than D2896) isn't a huge drop.

Charlie

Charlie

 

[Garak]

Originally Posted By: GreeshaK
New to oil talk, what does this mean?


Shear generally refers to the thinning of an oil. Yours is likely thinner due to fuel dilution. As others have pointed out in this thread and elsewhere, it's not always something to get alarmed about. If I ran 10 UOAs in a row with no shear, and then ran the 11th one and had a pile of fuel dilution, then I'd have something to worry about. Some engine designs are definitely different.

 

[The motor guy]

They dump tons of fuel for regeneration. My truck only gets about 8mpg while in regen. Obviously it's not a mercedes but just as an example. When not in regen it will get around 18 or so.

 

[The motor guy]

That thinned out bad. don't they call for a 5w40?

 

[BMWTurboDzl]

Originally Posted By: GreeshaK
Originally Posted By: BMWTurboDzl
Originally Posted By: m37charlie
Originally Posted By: BMWTurboDzl
Eh.. from what I've read the amount of fuel sent down to the DPF is minimal. I wonder if a leaky injector is the culprit. What do you think Charlie?


A leaky injector would be responsible for some black smoke at least before the oxi-cat heats up. I don't know for sure how much fuel is "post-injected" during active regeneration cycles but I suspect it is a fair amount judging from the fuel economy penalty. I dearly wish someone would make EGR/DPF delete kits for BMW and MB diesel cars.
As far as the TBN issue, ESP Formula M is a low starting TBN oil, I think in the 6.2-7.5 range. 3.7 isn't bad considering my "best guess" of 6.4 for starting. They don't publish it because it is so embarrassing.

Charlie
IIRC it's ~1% hit to FE. Do a search on the injection system (i cant from phone). The literature mentioned something about a single pulse of fuel being sent down the exhaust during Regen.



If you get a chance, please post the article you were referring to.
The poor fuel economy has to be linked to something in the exhaust system, because what else would explain mercedes designing a new engine and having worse economy. Honestly, with the amount of vehicles mercedes is dumping these engines into, the v6 has to be a solid engine.

You are both bmw guys, do you get a light that comes one when your dpf is regenerating? I have seen press photos of dpf lights in other mercedes vehicles, but have yet to see it come on in ours.

Also, maybe I missed something, but some articles say that mercedes adjusts engine permitters, and does not directly inject the fuel into the system. You guys say it sprays it rite in there. That still does not explain how it gets into the oil?
http://tis.spaghetticoder.org/s/view.pl?1/10/75/51

Try this. Link. My vehicle does not have a light and I've never noticed a drop in mpgs or performance when Regen was underway. The only time I've ever note ed Regen is when I exit the car and the aux fan is blowing to cool of the dpf along with a caramel smell.

 

[GreeshaK]

Originally Posted By: motor_oil_madman
That thinned out bad. don't they call for a 5w40?


yep, its got 5w40 in it

other than the viscosity after 5k miles, do the rest of the numbers look ok?

 

[NateDN10]

Originally Posted By: GreeshaK
Originally Posted By: motor_oil_madman
That thinned out bad. don't they call for a 5w40?


yep, its got 5w40 in it

other than the viscosity after 5k miles, do the rest of the numbers look ok?

Aside from the fuel dilution, your report looks great. Even if the dilution is artificially lowering wear numbers somewhat, I think you're still OK.

How is your driving style? If you do a lot of idling or low speed driving, this isn't really that surprising. If this is mostly long highway trips, the fuel dilution might indicate a problem.