Smell of fuel in new oil - BMW F800 Riders Forum & Registry



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  1. #1
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    F800R, year 2011 with 46 tkm. Changed the oil and filter last week with and after a week of driving I noticed a smell of gasoline in my oil. Can't say for sure, but I think that oil level is rising a bit. I also have a booster plug installed three years ago. Spark plugs have about 17tkm on them.
    Haven't noticed any smoke from the exaust, any lack of power and the bike starts without any problems, cold or hot. I really trashed it yesterday during the 1 hour drive trying to find any loss of power or anything but it ran like a charm. For all I know, I had a feeling it runs better than ever. I really enjoyed hitting max rev several times.
    Could it be that my booster plug has failed sending wrong signals and putting too much fuel?
    Could it be that injectors are failing and seeping fuel?
    My mechanic can't take my bike now, maybe in 10 days. He thinks that injectors have to be cleaned. He only works on BMW's but he was very surprised when I told him what my problem was.
    Would fuel additive help to maybe clean the injectors? I have these additive available at local shops but they are all for cars, none of them are for motorcycles. Is there any difference?

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  3. #2
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    You present one indicator (smell of fuel in the oil) and three contra-indicators (no issues starting, no loss of power, no smoke).

    Are you sure there is gas in the oil?
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    Where/when did you smell it?
    BMW F800ST, 2010, Black, Fuzeblock, Sat Nav, BMW Tank Bag, Givi Touring Screen, Denali Spotlights, Denali CANSmart, Wunderlich Crash Bars, 55K Miles & counting 

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    Quote Originally Posted by Runmyownlife View Post
    You present one indicator (smell of fuel in the oil) and three contra-indicators (no issues starting, no loss of power, no smoke).

    Are you sure there is gas in the oil?
    I can't be 100% sure, didn't send it for analysis. All I can state is that I can smell it.

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    Quote Originally Posted by DJ123 View Post
    Where/when did you smell it?
    I smelled it few days after oil change, when I checked the oil level. I can smell it on a dipstick and from inside the engine (where dipstick goes) and nowhere else. Today I went for a longer ride outside town and checked again after few hours and smell is still there but not as strong as before.

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    Have you noticed any difference in the engine performance, or economy?
    BMW F800ST, 2010, Black, Fuzeblock, Sat Nav, BMW Tank Bag, Givi Touring Screen, Denali Spotlights, Denali CANSmart, Wunderlich Crash Bars, 55K Miles & counting 

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    Quote Originally Posted by DJ123 View Post
    Have you noticed any difference in the engine performance, or economy?
    For all I know, the bike runs better then ever, maybe I got used to it after 3 years of riding. Went for another short ride yesterday, no problems. Economy is about the same. The only thing I can't get a proper reading is oil level. It's slightly above max when hot.
    I was very precise when I did the service, added 2.9L.
    Another mechanic said that I shouldn't change gears a lot when commuting and keep it in higher revs (4000-5000).
    I also haven't check my spark plugs. I was thinking I left them like they are for a proper mechanic do the diagnosis next week.
    Worried about the booster plug, maybe the mixture is too rich.

    Any suggestions on what I should ask my mechanic to check?

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    if the booster was the issue i would think the bike would throw an error code for the lambda sensor, if it was unable to correct the mixture/flow to a number it liked.

    The oil level will always vary, and unless a lot of fuel (or potentially coolant) was getting in you'd never know the difference.

    If your spark plugs were properly screwed you'd get misfiring and you'd notice uneven/lack of power.

    If your bike is riding no different i'd not be overly concerned. Run some injector cleaner through (weak mixture) for a tank or 2 and see if it helps.
    BMW F800ST, 2010, Black, Fuzeblock, Sat Nav, BMW Tank Bag, Givi Touring Screen, Denali Spotlights, Denali CANSmart, Wunderlich Crash Bars, 55K Miles & counting 

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    TL;DR - Send your oil off to be sampled.

    For what it's worth, I have an '08 F800ST and the first oil change I noticed it had a very strong fuel odor. I looked online and found others said the same and suggested, as long as the oil level remains consistent, don't worry about it.

    In any case, I sent the next oil change sample off to get analyzed and they did note a flashpoint of 365 when typical is >390. However, I informed them that I could not ride around for the 15 minute warmup as they suggested and instead let it warm up by idling for about 10 minutes (it was over this past winter). Here are their comments.

    This is a good first report for your F800ST. The only things slightly out of line are a bit of fuel, and the thin viscosity. A small amount of fuel like this could be related to idling for 5-10 minutes before sampling, so we're not too concerned about the fuel at this point. Fuel could also explain the slightly low viscosity, though this engine might have sheared the oil some as well. Other than those things, this is a glowing report. Wear metals are all below averages, which are based on ~3500-mile intervals, and there isn't any measurable coolant or water. Nice report.
    This is only the first report (I got the bike last year). The company sent me two more sample bottles so I'll definitely be sending a good sample (taken after the recommended warmup routine) and see if there is a pattern emerging. I'm pretty sure my results came 10 calendar days after I sent my sample in, and the sample kits are free so if you don't end up using it, no loss on your part. For the record, I used Blackstone Laboratories as they had very good reviews.

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    Quote Originally Posted by DJ123 View Post
    if the booster was the issue i would think the bike would throw an error code for the lambda sensor, if it was unable to correct the mixture/flow to a number it liked.

    The oil level will always vary, and unless a lot of fuel (or potentially coolant) was getting in you'd never know the difference.

    If your spark plugs were properly screwed you'd get misfiring and you'd notice uneven/lack of power.

    If your bike is riding no different i'd not be overly concerned. Run some injector cleaner through (weak mixture) for a tank or 2 and see if it helps.
    Thank you for your answer and your patience, that helps a lot.

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    Quote Originally Posted by gberl001 View Post
    TL;DR - Send your oil off to be sampled.

    For what it's worth, I have an '08 F800ST and the first oil change I noticed it had a very strong fuel odor. I looked online and found others said the same and suggested, as long as the oil level remains consistent, don't worry about it.

    In any case, I sent the next oil change sample off to get analyzed and they did note a flashpoint of 365 when typical is >390. However, I informed them that I could not ride around for the 15 minute warmup as they suggested and instead let it warm up by idling for about 10 minutes (it was over this past winter). Here are their comments.



    This is only the first report (I got the bike last year). The company sent me two more sample bottles so I'll definitely be sending a good sample (taken after the recommended warmup routine) and see if there is a pattern emerging. I'm pretty sure my results came 10 calendar days after I sent my sample in, and the sample kits are free so if you don't end up using it, no loss on your part. For the record, I used Blackstone Laboratories as they had very good reviews.
    Thanks, I would like to test my oil to see if something is wrong just to be sure.
    I'll try to find a company inside EU that does that. If not, I'll send my sample to Blackstone. Looks like they know what they are doing.

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    Just a follow up, I try to finish all of my threads if I can to help someone in the future with same or similar problem.
    Got back from my mechanic shop. He did a full diagnostic check, no faults found, bike is running fine.
    Regarding the oil and the smell, he says that he can't smell fuel but thinks that oil is burning a bit, hence the strange smell. I used Silikolene Pro 4 XP 15W50 on my last change (got only 1000 Km's on this oil). I switched from Motul 7100 15W50 (never had this smell problem with this oil). His recommendation is that I switch back to Motul and I'll do that next week and get back to you with results.

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