Fuel Dilution "Burn-Off"

[doyall]

My experience with fuel dilution and burn off is that it does not happen to a satisfactory degree to mitigate the problem. See the attached VOA's. Sample number 7 was done immediately after a one stop, 100 mile each way trip. Reduction, but not elimination. And it would immediately return after 'normal' usage (10 mile commute). Even after an oil change (sample 9) followed by a one mile drive it was unacceptably diluted in my mind. And look at sample 10 after that same 100-mile-each-way-with-one-stop trip. Got tired of fighting Mercedes-Benz and got rid of the car. Same story with a previously owned '11 3.0L General Motors High Feature V6.

My theory was that none of the manufactures run the oil hot enough to evaporate all the gas constituents that will in fact evaporate. This theory may be somewhat supported with the current vehicle ('17 Jeep Grand Cherokee 3.6L Pentastar V6 with MPI - not DI) which has an oil temperature display. Oil temperature rarely gets to 200*F. Normally hovers between 185* and 195* depending on outside temperature and usage stress. I suppose this is done in order to be able to extend oil interval changes and maybe so that the actual viscosity at operating temperature will remain acceptable (especially when 0W-20 is specified)?

Oh, the gas chromatography is, in my opinion, the only way to get an accurate fuel dilution number. Forget about the flash point interpretation. Got the testing to convince myself of that.

 

[Danh]

doyall, thanks for posting the used oil analysis. Nice to know (well, sort-of) that this is a common DI condition, but it leaves those of us bothered by it with few auto alternatives. Despite the fuel dilution, your wear metals look fine, as do mine. It would sure be helpful if manufacturers would publish something to increase our comfort level - it wouldn't even have to be manufacturer-specific - a trade group speaking on behalf of the industry would be fine.

And your fight with MB sounds a lot like mine with Honda: won't acknowledge a used oil analysis may be valid, won't acknowledge there's a problem but also won't acknowledge it's normal.

Also interesting to note MB hasn't jumped on the "low calcium for LSPI mitigation" bandwagon.

 

[dblshock]

I just spoke with the service manager and sent him my used oil analysis, he claims to have heard of the issue but not with any Honda brand motors. this is a large metro dealer...requested a plan to deal with this critical dilution flagged by Polaris after only 4,350mi.

 

[kschachn]

Originally Posted By: dblshock
I just spoke with the service manager and sent him my used oil analysis, he claims to have heard of the issue but not with any Honda brand motors. this is a large metro dealer...requested a plan to deal with this critical dilution flagged by Polaris after only 4,350mi.


Which Honda dealership are you working with? One in Milwaukee, Madison or Kenosha? Not all are the same, and in fact some are far better than others.

 

[doyall]

Originally Posted By: Danh
... And your fight with MB sounds a lot like mine with Honda: won't acknowledge a used oil analysis may be valid, won't acknowledge there's a problem but also won't acknowledge it's normal. ...


Oh yeah, they all have the same playbook. My plight is well documented over at the GLAowners forum and the SRXforum (IIRC). One member at GLAowners did point me to this SAE paper: http://papers.sae.org/2015-01-0967/ (Impact of Fuel Injection on Dilution of Engine Crankcase Oil for Turbocharged Gasoline Direct-Injection Engines) which is very reveling. Unfortunately it costs $27 and is copyrighted or I would reproduce it here. I will save you the cost, our concerns are verified by engineers.

 

[barryh]

I have a short commute of 4 miles to work which during winter will produce mayonnaise inside the valve cover. The solution I've adopted is to let the engine breath at the end of the journey by removing the oil filler cap in the garage. It's a real pain to have to do it but it does allow moisture to evaporate off and any mayonnaise disappears overnight. I no longer subject my current car to these short trips but still remove the oil filler on the bike every night without fail.

Would this practice not help with fuel dilution.

 

[Danh]

Originally Posted By: dblshock
I just spoke with the service manager and sent him my used oil analysis, he claims to have heard of the issue but not with any Honda brand motors. this is a large metro dealer...requested a plan to deal with this critical dilution flagged by Polaris after only 4,350mi.


Here's my prediction: they'll check for trouble codes, make sure you're running the current software, look at fuel trim by cylinder and run a gasoline "sniffer" around the engine bay. All will be well and they'll send you on your way with instructions to come back only if you have a CEL or an engine catastrophe. They will not acknowledge your level of fuel dilution is typical but will say your engine is functioning as intended.

To be fair to Honda, there are lots of safeguards built into the diagnostic system to identify actual, fixable problems that could contribute to fuel dilution and if none of them trigger a warning they won't have a remedy. Doesn't mean there isn't an issue, but Honda won't put much effort into chasing issues like this for an individual. On the plus side, at least the issue will,be documented.

 

[dblshock]

Honda City West Allis, WI.: here's e.mail sent today

Hi Jeff

Per our conversation my oil level is rising at an alarming rate, if filled to half way between the low/full mark on the dipstick it will go hyperbolic over the orange plastic within 2000 miles (see pic). Curious, I sent a used oil sample to have analyzed at 4,300mi. (see .pdf) and sure enough came back as severe fuel dilution. I’m wondering how to deal with this problem as changing oil every 1,800 mile would be costly and time consuming, ignoring it will certainly be trouble. Please contact me with a resolution plan.

Thank You

 

[dblshock]

this filthy little 1.5t pulls this in 2000mi.

 

[SonofJoe]

Originally Posted By: Ducked
Couple of points I find a bit confusing

"Hot blow-by is the gas phase stripping medium in an engine."

Fair enough, that's what I thought. Bur your earlier example (and the acceptance of the chip pan as a valid analogy) seemed to be suggesting that the fuel vapour was the gas stripping phase.

"The steam and the various components that make up vegetable oil, will all exert their own individual vapour pressure and the mole fractions of each in the aggregate equilibrium vapour flow from the surface of the chip pan will be set according to the gas laws. The more volatile components of the chip oil will preferentially enter the gas phase just as the lightest fractions of the base oil in engine oil."

That seems to be a description of fractional distillation, and it seems to be saying that the different fractions behave independently, (which is what I thought) whereas earlier you seemed to be saying that the fuel and the light oil fractions interact.



In fairness, I did say it was complicated...

Classical fractional distillation is what you might do to something like crude oil. There are thousands of individual hydrocarbons in crude ranging from propane to the heaviest multi-ring asphaltene. You can't separate all the individual species so you simply distil the crude into 'fractions' as defined by boiling range. In fractional distillation, you only distil one thing (crude oil) by repeated heating/evaporation and cooling/condensation. There is no stripping medium. The physics of vapour pressure and the gas laws does the rest.

Stripping is a form of 'extractive' distillation. It's characterised by the introduction of a distinct, primarily non-condensing gas phase. This gas phase serves to provide a 'space' for volatile liquids to evaporate into. Stripping is usually a single stage process as opposed to classical distillation which is multi stage.

In engines, the stripping of fuel, water and light base oil from lubricant is complicated because the stripping medium can partly condense. The bulk of the blow-by gas (nitrogen, excess oxygen, carbon dioxide and monoxide) will be essentially non-condensing. However it also contains water and unburnt/partially burnt fuel, and too a much lesser extent, nitrous oxide, which CAN condense depending on the temperature of the engine oil they are contacted with.

It helps if you think about fuel and water as being the jam in a sandwich where the two slices of bread are a non-condensing gas (the bulk of the blow-by) on top and a non-volatile liquid (the bulk of the engine oil) underneath. Whether the jam sticks to the bottom slice or the top slice depends on whether the sandwich is kept in the fridge or put under the grill. What catches a lot of people out is that if you have too much jam in the sandwich and put it under the grill, that some of the bread in the bottom slice, can with the aid of the jam, migrate into the top slice! Magic!!

 

[Ducked]

Originally Posted By: SonofJoe

It helps if you think about fuel and water as being the jam in a sandwich ...






I'm from Scotland.

I can only relate to deep-fried analogies.

 

[Ducked]

Originally Posted By: barryh
I have a short commute of 4 miles to work which during winter will produce mayonnaise inside the valve cover. The solution I've adopted is to let the engine breath at the end of the journey by removing the oil filler cap in the garage. It's a real pain to have to do it but it does allow moisture to evaporate off and any mayonnaise disappears overnight. I no longer subject my current car to these short trips but still remove the oil filler on the bike every night without fail.

Would this practice not help with fuel dilution.


I suggested doing that here (with some minor suggested technical enhancements):-

https://bobistheoilguy.com/forums/ubbthreads.php/topics/4284467/Little_Used_Vehicles#Post4284467

based mostly on a discussion on a light aircraft site.

Nobody liked the idea.

Going further I suppose you'd be steam stripping, or heating and flushing with an inert, dry gas.

Perhaps if you ran a brewery?

 

[SonofJoe]

Originally Posted By: dblshock
Honda City West Allis, WI.: here's e.mail sent today

Hi Jeff

Per our conversation my oil level is rising at an alarming rate, if filled to half way between the low/full mark on the dipstick it will go hyperbolic over the orange plastic within 2000 miles (see pic). Curious, I sent a used oil sample to have analyzed at 4,300mi. (see .pdf) and sure enough came back as severe fuel dilution. I’m wondering how to deal with this problem as changing oil every 1,800 mile would be costly and time consuming, ignoring it will certainly be trouble. Please contact me with a resolution plan.

Thank You



I'm not 'mechanical' so I'm not sure what I'm about to say is feasible...

However from a theoretical point of view, if your engine is dumping this much fuel into your engine oil, and it's just causing the sump level to rise and rise, then my gut feel is that the oil is not getting anywhere like hot enough during normal use to effect proper conditions for fuel strip. Typically it should be getting up to 100 to 110°C. If, for whatever reason, it's not getting above 50 to 60°C, then you're probably not getting any meaningful strip-out. If this is correct, the first thing I'd ask Honda to look at is the set-point of your coolant system thermostat. My gut feel is yours might be set on the low side. The easiest way to get your oil hotter is to increase your thermostat temperature. Obviously you can't go above 100°C or the coolant will boil but if you could get it so that it opens around the 85 - 90°C mark, you might find this impacts positively on the oil temperature. If the thermostat is already set at this temperature, I might ask myself if the thermostat is simply defective, running open all the time and simply causing the engine to run permanently cold. You might also ask Honda to confirm the PCV valve is opening correctly. The strip out mechanism only works if the saturated blow-by has an open route to the intake system. If the valve is stuck shut or gunked-up, the fuel simply has nowhere to go.

Hope this helps.

 

[SonofJoe]

Originally Posted By: Ducked
Originally Posted By: SonofJoe

It helps if you think about fuel and water as being the jam in a sandwich ...






I'm from Scotland.

I can only relate to deep-fried analogies.



Imagine a deep-fried Mars Bar sandwiched between two slices of fried bread....

 

[Ducked]

Originally Posted By: SonofJoe
Originally Posted By: Ducked
Originally Posted By: SonofJoe

It helps if you think about fuel and water as being the jam in a sandwich ...






I'm from Scotland.

I can only relate to deep-fried analogies.



Imagine a deep-fried Mars Bar sandwiched between two slices of fried bread....


Mmmm...nostalgia. No imagination required.

 

[Ducked]

Originally Posted By: SonofJoe
Obviously you can't go above 100°C or the coolant will boil...


Think you can a bit, because:-

(a) Its a pressurised system, so, for example, if it was running at 15 psi, the boiling point of water would be 120C

(b) It isn't running pure water, but usually 50/50 ethylene glycol/water, which I've seen with quoted boiling points ranging from 106 to 115C at atmospheric pressure, with the lower temp more commonly quoted. Coolant at 15 psi is said to boil around 125C

I suppose you could in theory produce "tuned" increases in the boiling point of your coolant by going higher than 50% antifreeze. This would reduce the coolant heat capacity though, so you'd have to sure the system had the flow rate and radiator size to cope. Honda might not be prepared to endorse such a practice.

However, according to this lot

http://www.stant.com/index.php/english/products/consumer-products/thermostats/abcs-thermostats/

(who are probably American since they think "applicated" is a verb)

"Alternate temperature are not applicated for most newer vehicles. Using an alternate temperature thermostat in a newer vehicle would require changing computer setting and possible additional modifications"


I could have one though.

 

[Danh]

Originally Posted By: SonofJoe
Originally Posted By: dblshock
Honda City West Allis, WI.: here's e.mail sent today

Hi Jeff

Per our conversation my oil level is rising at an alarming rate, if filled to half way between the low/full mark on the dipstick it will go hyperbolic over the orange plastic within 2000 miles (see pic). Curious, I sent a used oil sample to have analyzed at 4,300mi. (see .pdf) and sure enough came back as severe fuel dilution. I’m wondering how to deal with this problem as changing oil every 1,800 mile would be costly and time consuming, ignoring it will certainly be trouble. Please contact me with a resolution plan.

Thank You



I'm not 'mechanical' so I'm not sure what I'm about to say is feasible...

However from a theoretical point of view, if your engine is dumping this much fuel into your engine oil, and it's just causing the sump level to rise and rise, then my gut feel is that the oil is not getting anywhere like hot enough during normal use to effect proper conditions for fuel strip. Typically it should be getting up to 100 to 110°C. If, for whatever reason, it's not getting above 50 to 60°C, then you're probably not getting any meaningful strip-out. If this is correct, the first thing I'd ask Honda to look at is the set-point of your coolant system thermostat. My gut feel is yours might be set on the low side. The easiest way to get your oil hotter is to increase your thermostat temperature. Obviously you can't go above 100°C or the coolant will boil but if you could get it so that it opens around the 85 - 90°C mark, you might find this impacts positively on the oil temperature. If the thermostat is already set at this temperature, I might ask myself if the thermostat is simply defective, running open all the time and simply causing the engine to run permanently colld. You might also ask Honda to confirm the PCV valve is opening correctly. The strip out mechanism only works if the saturated blow-by has an open route to the intake system. If the valve is stuck shut or gunked-up, the fuel simply has nowhere to go.

Hope this helps.



My fuel-diluting Honda CRV shares the K24W engine with the Accord. Interestingly, the 2016 Accord thermostat has a full-open temperature 10F higher than earlier Accords and 2015-2016 CRVs. I suppose there could be several reasons for this change but, as you note, it would help to reduce residual fuel dilution.

I believe the OBDII system monitors coolant temperature and will trigger a CEL if it doesn't get to the correct temperature in a specified period of time given starting and ambient air temperature, so a stuck or slow-opening thermostat should be noticed. But it's still worth dblshock asking the question.

 

[LotI]

Originally Posted By: Danh
Originally Posted By: SonofJoe
Originally Posted By: dblshock
Honda City West Allis, WI.: here's e.mail sent today

Hi Jeff

Per our conversation my oil level is rising at an alarming rate, if filled to half way between the low/full mark on the dipstick it will go hyperbolic over the orange plastic within 2000 miles (see pic). Curious, I sent a used oil sample to have analyzed at 4,300mi. (see .pdf) and sure enough came back as severe fuel dilution. I’m wondering how to deal with this problem as changing oil every 1,800 mile would be costly and time consuming, ignoring it will certainly be trouble. Please contact me with a resolution plan.

Thank You



I'm not 'mechanical' so I'm not sure what I'm about to say is feasible...

However from a theoretical point of view, if your engine is dumping this much fuel into your engine oil, and it's just causing the sump level to rise and rise, then my gut feel is that the oil is not getting anywhere like hot enough during normal use to effect proper conditions for fuel strip. Typically it should be getting up to 100 to 110°C. If, for whatever reason, it's not getting above 50 to 60°C, then you're probably not getting any meaningful strip-out. If this is correct, the first thing I'd ask Honda to look at is the set-point of your coolant system thermostat. My gut feel is yours might be set on the low side. The easiest way to get your oil hotter is to increase your thermostat temperature. Obviously you can't go above 100°C or the coolant will boil but if you could get it so that it opens around the 85 - 90°C mark, you might find this impacts positively on the oil temperature. If the thermostat is already set at this temperature, I might ask myself if the thermostat is simply defective, running open all the time and simply causing the engine to run permanently colld. You might also ask Honda to confirm the PCV valve is opening correctly. The strip out mechanism only works if the saturated blow-by has an open route to the intake system. If the valve is stuck shut or gunked-up, the fuel simply has nowhere to go.

Hope this helps.



My fuel-diluting Honda CRV shares the K24W engine with the Accord. Interestingly, the 2016 Accord thermostat has a full-open temperature 10F higher than earlier Accords and 2015-2016 CRVs. I suppose there could be several reasons for this change but, as you note, it would help to reduce residual fuel dilution.

I believe the OBDII system monitors coolant temperature and will trigger a CEL if it doesn't get to the correct temperature in a specified period of time given starting and ambient air temperature, so a stuck or slow-opening thermostat should be noticed. But it's still worth dblshock asking the question.


For reference...

My Scanguage II reports and operating temp of 80C/170F in my Accord. The oil would have to be significantly hotter than the coolant to burn anything off. I doubt it is. A used oil analysis done at 5k miles of oil use showed 2%fuel.

My Ford however reports 90C/193F, which is more my experience with modern engines.

 

[Danh]

Originally Posted By: LotI
Originally Posted By: Danh
Originally Posted By: SonofJoe
Originally Posted By: dblshock
Honda City West Allis, WI.: here's e.mail sent today

Hi Jeff

Per our conversation my oil level is rising at an alarming rate, if filled to half way between the low/full mark on the dipstick it will go hyperbolic over the orange plastic within 2000 miles (see pic). Curious, I sent a used oil sample to have analyzed at 4,300mi. (see .pdf) and sure enough came back as severe fuel dilution. I’m wondering how to deal with this problem as changing oil every 1,800 mile would be costly and time consuming, ignoring it will certainly be trouble. Please contact me with a resolution plan.

Thank You



I'm not 'mechanical' so I'm not sure what I'm about to say is feasible...

However from a theoretical point of view, if your engine is dumping this much fuel into your engine oil, and it's just causing the sump level to rise and rise, then my gut feel is that the oil is not getting anywhere like hot enough during normal use to effect proper conditions for fuel strip. Typically it should be getting up to 100 to 110°C. If, for whatever reason, it's not getting above 50 to 60°C, then you're probably not getting any meaningful strip-out. If this is correct, the first thing I'd ask Honda to look at is the set-point of your coolant system thermostat. My gut feel is yours might be set on the low side. The easiest way to get your oil hotter is to increase your thermostat temperature. Obviously you can't go above 100°C or the coolant will boil but if you could get it so that it opens around the 85 - 90°C mark, you might find this impacts positively on the oil temperature. If the thermostat is already set at this temperature, I might ask myself if the thermostat is simply defective, running open all the time and simply causing the engine to run permanently colld. You might also ask Honda to confirm the PCV valve is opening correctly. The strip out mechanism only works if the saturated blow-by has an open route to the intake system. If the valve is stuck shut or gunked-up, the fuel simply has nowhere to go.

Hope this helps.



My fuel-diluting Honda CRV shares the K24W engine with the Accord. Interestingly, the 2016 Accord thermostat has a full-open temperature 10F higher than earlier Accords and 2015-2016 CRVs. I suppose there could be several reasons for this change but, as you note, it would help to reduce residual fuel dilution.

I believe the OBDII system monitors coolant temperature and will trigger a CEL if it doesn't get to the correct temperature in a specified period of time given starting and ambient air temperature, so a stuck or slow-opening thermostat should be noticed. But it's still worth dblshock asking the question.


For reference...

My Scanguage II reports and operating temp of 80C/170F in my Accord. The oil would have to be significantly hotter than the coolant to burn anything off. I doubt it is. A used oil analysis done at 5k miles of oil use showed 2%fuel.

My Ford however reports 90C/193F, which is more my experience with modern engines.


Just as a guess, the used oil analysis was performed by Blackstone?

 

[dblshock]

weekly I operate from Lat. 43-46 so it's cold but the heater works fine and no CEL..I'll have them check the temps, thx.