Evaporation of gasoline in engine oil

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It obvious, of course, that gasoline in an open container will evaporate quickly while gasoline in a sealed container will not.

So, if a sump (a closed system) of gasoline-contaminated oil were exposed to air would the gasoline evaporate as well? Or would gasoline's miscibility with engine oil make this not possible?

I ask the question because when I withdraw the dipstick on my fuel-diluting Honda K24W I'm usually hit with a strong gasoline odor. So one wonders if the oil could be "cleansed" of its gasoline contamination by pulling the dipstick while the car was parked. I realize this could take a very long time, but is it conceptually possible?
 
The PCV system pulls fresh air through the crankcase constantly when the engine is running. Pulling the dipstick isn't going to move much air and since gas vapors are heavy anyway...

I wouldn't do it. Too easy to forget and coat the engine bay with a fine mist of oil.

Used oil will always have a hydrocarbon fuel smell to it. It gets contaminated by blow-by and fuel when the engine runs. It's normal. The best thing to do is drive it on the highway for an hour and let the oil get up to 100C

The gas will evaporate and be drawn back into the intake by the PCV system.
 
If it smells like fuel when checking the oil, then even if it evaporated through use, it sounds like more fuel is being added, so it technically will always be there.
 
Yes, these Hondas dilute fuel even during highway driving, so getting the oil up to operating temperature isn't a cure as new fuel dilution occurs despite some vapors presumably being boiled- off.
 
I have read that running higher octane fuel can reduce dilution as the ecu can run a leaner mixture. High compression GDI on 87 run rich mixtures to control knock, which contributes to dilution
 
There would be some evaporation or vaporization when the engine is running due to the splash effect and all the moving parts.
 
Aquarium pump. Bubble filtered (and ideally dried) air through it. But it wont shift much of the heavy end, and it might increase your oil oxidation rate a little.

Get into home brewing/moonshining on a large scale and you could bubble CO2 through it, but you'd have to dry it.
 
Originally Posted By: Ducked
Aquarium pump. Bubble filtered (and ideally dried) air through it. But it wont shift much of the heavy end, and it might increase your oil oxidation rate a little.

Get into home brewing/moonshining on a large scale and you could bubble CO2 through it, but you'd have to dry it.


That would mess up the air/fuel ratio if the PCV started sucking up CO2
 
Originally Posted By: Danh
Yes, these Hondas dilute fuel even during highway driving, so getting the oil up to operating temperature isn't a cure as new fuel dilution occurs despite some vapors presumably being boiled- off.


But greater fuel dilution occurs at cold starts? For example, if a person is taking numerous short duration trips then is there a greater amount of fuel dilution than if they are commuting 40-60 minutes at a time?

If so, then the question becomes at what rate does the fuel get returned through the PCV vs the rate it is getting past the rings on a highway trip.

I have a CRV with 170K miles and my typical commute is 40 miles. I don't have a gas smell at my dipstick.
That is the reason I am asking about this.

Thanks
 
Originally Posted By: SilverFusion2010
Originally Posted By: Ducked
Aquarium pump. Bubble filtered (and ideally dried) air through it. But it wont shift much of the heavy end, and it might increase your oil oxidation rate a little.

Get into home brewing/moonshining on a large scale and you could bubble CO2 through it, but you'd have to dry it.


That would mess up the air/fuel ratio if the PCV started sucking up CO2


Not sure if you're serious (not sure if I am either) but this would be for static use in your garage with the engine off.

In another thread on this topic steam stripping was suggested, I think for while the engine was running and at operating temperature.That would require the temperature to be kept high to avoid condensation accumulation.
 
SilverFusion mentioned reading about some success with running higher octane fuel. I have also heard this and some have commented here and on a Mazda forum I lurk in that it does work.

Next time you change your oil, why not start running premium fuel? Yes it's expensive but it would be a good opportunity for you to compare and then share your findings.
 
Originally Posted By: PimTac
SilverFusion mentioned reading about some success with running higher octane fuel. I have also heard this and some have commented here and on a Mazda forum I lurk in that it does work.

Next time you change your oil, why not start running premium fuel? Yes it's expensive but it would be a good opportunity for you to compare and then share your findings.


It does seem to help and I'll give it another try. At its most extreme, fuel dilution shows up in my Honda as an increase in oil level. Interestingly, this typically occurs at Interstate speeds driving into a stiff headwind. With the very high gearing and the good amount of frontal area on these cars it's possible preignition is occurring and fuel enrichment, rather than retarding spark, is the PCM's solution. So premium may help.

Evaporation would still be a nice solution...
 
Originally Posted By: ArcticDriver
Originally Posted By: Danh
Yes, these Hondas dilute fuel even during highway driving, so getting the oil up to operating temperature isn't a cure as new fuel dilution occurs despite some vapors presumably being boiled- off.


But greater fuel dilution occurs at cold starts? For example, if a person is taking numerous short duration trips then is there a greater amount of fuel dilution than if they are commuting 40-60 minutes at a time?

If so, then the question becomes at what rate does the fuel get returned through the PCV vs the rate it is getting past the rings on a highway trip.

I have a CRV with 170K miles and my typical commute is 40 miles. I don't have a gas smell at my dipstick.
That is the reason I am asking about this.

Thanks


I'll guess your CRV is a 2014 or earlier? Honda switched CRVs to direct injection in 2015 which is the cause of fuel dilution.
 
On my V8 Taurus SHO I ran a catch can and sealed off the fresh air intake flow for the PCV system. When under normal driving it would make about 7"Hg of vacuum. This helped pull out the vapors.
 
Originally Posted By: jongies3
Engine should get hot enough to burn off any fuel in the oil I'd think.


Gasoline is made up of "Lights" and Heavies" and everything in between.

The "lights" evaporate off when the oils heats up, and get sucked through the PCV into the intake.

the "heavies" have a much higher boiling temp, and have a tendency to stick around.

Theoretically, you could drain the oil, heat it up to 300*F (a safe temp for most all engine oil" and that might help get rid of some of the "heavies" that make the oil on the dipstick smell so much like gas.
 
Originally Posted By: Linctex
Originally Posted By: jongies3
Engine should get hot enough to burn off any fuel in the oil I'd think.


Gasoline is made up of "Lights" and Heavies" and everything in between.

The "lights" evaporate off when the oils heats up, and get sucked through the PCV into the intake.

the "heavies" have a much higher boiling temp, and have a tendency to stick around.

Theoretically, you could drain the oil, heat it up to 300*F (a safe temp for most all engine oil" and that might help get rid of some of the "heavies" that make the oil on the dipstick smell so much like gas.


Spot on...

 
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