Oil Analysis shows &% fuel in oil???

[ajm55]

So I have a 2013 Comp Pack, running a BPM tune, dps and intakes. Our fuel is sub-standard, so I always add either 10% ethanol or a good octane booster when re-fueling.

I change the oil annually and cover about 4,000 kms in a year. I use Ravenol VST 5w40.

The car's done 80,000 kms.

Below is a lab report of an oil analysis done last week. The oil was drained after 4,000 kms.

I am surprised by the results. The report indicates that the sample oil had just about exhausted its lifespan and that it had 7% of fuel. It is suggested that I check the fuel system.

My questions:

1)Am I correct that if there is an issue with the fuel system causing the ingress of excess fuel into the oil, the only possibilities are faulty injectors and/or fuel pumps?

2) The car doesn't miss a beat. Idles smoothly from cold start and goes like the clappers. My LTFTs and STFTs indicate no issues at all. My HPFPs churn out similar pressures - between 6500 and 7500 psi at idle and around 2,900 psi under WOT. Would my data logs not indicate some irregularity or another or would the car not run less than perfectly if there were an underlying issue with either the injectors or the HPFPs?

3) My car is fitted with EU5 injectors. If I do need to change all of them, can I use EU6?

4) Are the OE injectors manufactured by Bosch? If so, does anyone have the Bosch part number?

Cheers


[ATTACH][/ATTACH]

[AlisterB]

Do you do lots of short trips in it?

[ajm55]

Originally Posted by AlisterB

Do you do lots of short trips in it?

Not at all. It's a weekend car and the oil will almost invariably reach operating temperature on each trip. I've just spoken to a local tuner who reckons the most likely cause (given that my car runs perfectly and shows no signs of a misfire) is a leaking HPFP. That would make sense and is first on my list to have checked.

[lucid21]

I don't claim the know the source of the issue, but if your car has a tune in it, I would think about that as well. To the best of my knowledge, tuning entails revising injector firing durations (at least it does on my E30 M3 tune; I have full access to the fuel map). Now what are the implications of that in terms of having fuel in your oil? I don't fully know as it probably depends on how that duration overlaps with the cylinder position, how fuel gets (or does not get) burned throughout that process etc. If that may be a/the cause, replacing the injectors will not change anything. That doesn't mean your injectors are good (not "sticky") though, which is also a possibility.

[ajm55]

Originally Posted by lucid21

I don't claim the know the source of the issue, but if your car has a tune in it, I would think about that as well. To the best of my knowledge, tuning entails revising injector firing durations (at least it does on my E30 M3 tune; I have full access to the fuel map). Now what are the implications of that in terms of having fuel in your oil? I don't fully know as it probably depends on how that duration overlaps with the cylinder position, how fuel gets (or does not get) burned throughout that process etc. If that may be a/the cause, replacing the injectors will not change anything. That doesn't mean your injectors are good (not "sticky") though, which is also a possibility.

Thanks. Yes, the car is tuned and I do understand that that might contribute to fuel dilution. However, the lab report indicates that the oil's useful life had all but been exhausted within its 4,000 kms of use. That is extreme and points to a co-contributor of some kind.

[lucid21]

Originally Posted by ajm55

Thanks. Yes, the car is tuned and I do understand that that might contribute to fuel dilution. However, the lab report indicates that the oil's useful life had all but been exhausted within its 4,000 kms of use. That is extreme and points to a co-contributor of some kind.

I guess that depends on the reason as to why the oil's useful life has been exhausted. You mention "co-contributor" above but there may very well be a single cause explaining all this. As in, whatever may be causing the fuel in oil problem may be the also causing the oil to be used up--although I am not sure what that means in technical terms. It may be worth flashing the ECU back to stock and repeating the test. Or I guess you can replace your injectors and repeat the test, too. Either way, without having a solid thesis on the cause, this may turn into an expensive trial and error diagnostic process. Final thought: you can try dropping the octane booster first. Not sure why you are adding it. Do you not the trust the industrial process that is giving the fuel you buy (where you are) the octane rating it has? So what if it has ethanol in it? The octane rating is what it is. It should be fine as long as it meets BMW's specification. Not sure why you want to increase the octane rating beyond that unless you messed with your engine's compression ratio. But then you have a tune on it, so who knows what that is doing exactly...Good luck.

[ajm55]

Originally Posted by lucid21

I guess that depends on the reason as to why the oil's useful life has been exhausted. You mention "co-contributor" above but there may very well be a single cause explaining all this. As in, whatever may be causing the fuel in oil problem may be the also causing the oil to be used up--although I am not sure what that means in technical terms. It may be worth flashing the ECU back to stock and repeating the test. Or I guess you can replace your injectors and repeat the test, too. Either way, without having a solid thesis on the cause, this may turn into an expensive trial and error diagnostic process. Final thought: you can try dropping the octane booster first. Not sure why you are adding it. Do you not the trust the industrial process that is giving the fuel you buy (where you are) the octane rating it has? So what if it has ethanol in it? The octane rating is what it is. It should be fine as long as it meets BMW's specification. Not sure why you want to increase the octane rating beyond that unless you messed with your engine's compression ratio. But then you have a tune on it, so who knows what that is doing exactly...Good luck.

I speculate that there is a co-contributor because an oil analysis done by the same lab in 2020 on oil that had covered slightly more distance while running the same tune and ethanol/pg mix showed a 3% fuel dilution factor - which is considered acceptable.

I add octane booster / ethanol because our fuel (which has no ethanol content) is sub-standard. It is probably the equivalent of 90 octane in the USA and I see loads of timing pull when not adding octane in some form or another.

I have now replaced the injectors and will have another oil analysis done in about 4,000 kms to assess.

[lucid21]

I misread your initial post. I thought you were adding octane booster because the fuel has ethanol. Good luck with diagnosing the issue and keep us posted.

[samuusa]

Hello,

Any updates? I'm curious because I've been having a strong smell of fuel on my oil changes and I do about 5000-6000 kms/1 year between oil changes.

My M5 is at 165xxx km now and I changed all of the injectors to EU5 Bosch ones. Approx. 3 years ago when it had 110000 kms on the clock.

I also use Ravenol VST 5w40 oil. Measured the oil physically, because I do not trust the oil level sensor to be correct, and I lose about 1L of oil/5000 km.


Anyway, please let me know if replacing your injector has fixed the fuel dilution.

[ajm55]

Originally Posted by samuusa

Hello,

Any updates? I'm curious because I've been having a strong smell of fuel on my oil changes and I do about 5000-6000 kms/1 year between oil changes.

My M5 is at 165xxx km now and I changed all of the injectors to EU5 Bosch ones. Approx. 3 years ago when it had 110000 kms on the clock.

I also use Ravenol VST 5w40 oil. Measured the oil physically, because I do not trust the oil level sensor to be correct, and I lose about 1L of oil/5000 km.


Anyway, please let me know if replacing your injector has fixed the fuel dilution.

I replaced the HPFPs and injectors with new OE parts and did another oil change. The car drives the same as before although my fuel consumption has improved a little. I will send another oil sample off to the lab for analysis on my next oil change.

[sgtfury40]

Make sure you resolve the fuel in oil issue. I had an e90 335i with a leaky injector. it leaked fuel after turn-off into cylinder, past the rings, and into the oil. Diluted the viscosity enough that I ended up with bearing damage. Ended up getting another 335i rather than repair the engine; it was too costly.