I've spent far too much time wandering the internet trying to better understand the causes, effects and remedies for fuel dilution of engine oil, particularly in DI/TGDI engines. My Honda CRV is one of these and certainly has the issue.
One of the oft-repeated bits of advice here is that a periodic highway run will "burn-off" fuel that accumulates in the sump. The attached document from the State Of Michigan seems to partly refute this notion.
Most of us presume gasoline is a pretty uniform product and, as it's really flammable, should be volatile and evaporate quickly with any temperature, even when mixed with engine oil. But, as the attached table illustrates, gasoline has many different components that evaporate at different temperatures.
The purpose of this table is to point out seasonal variations in gas blends for Michigan's climate. But to me, the really important point is that, in most months, temperatures of 170-250F are needed to evaporate 50% of the fuel. And to evaporate 90%, temperatures greater than 365F are needed.
Given typical, fully-warmed up gasoline engine sump temperatures are maybe 200-225F, it seems to me that, even with lots of highway driving we'd be lucky to eliminate 1/2 of any fuel dilution. The remainder would stick around for the remainder of the OCI. Given this, dilution levels may not plateau at some point but could steadily increase over time, even with highway driving. As the text above the table says, some of the effects of higher evaporation temperatures are: "...increased deposits and dilution of engine oil".
I acknowledge I could have this wrong, but it is supported by my personal experience: even after a very long Interstate drive, my DI Honda still shows fuel dilution >5%. It seems to me the only real solution for owners of chronic fuel diluters is frequent oil changes.
Thoughts? Thanks.
One of the oft-repeated bits of advice here is that a periodic highway run will "burn-off" fuel that accumulates in the sump. The attached document from the State Of Michigan seems to partly refute this notion.
Most of us presume gasoline is a pretty uniform product and, as it's really flammable, should be volatile and evaporate quickly with any temperature, even when mixed with engine oil. But, as the attached table illustrates, gasoline has many different components that evaporate at different temperatures.
The purpose of this table is to point out seasonal variations in gas blends for Michigan's climate. But to me, the really important point is that, in most months, temperatures of 170-250F are needed to evaporate 50% of the fuel. And to evaporate 90%, temperatures greater than 365F are needed.
Given typical, fully-warmed up gasoline engine sump temperatures are maybe 200-225F, it seems to me that, even with lots of highway driving we'd be lucky to eliminate 1/2 of any fuel dilution. The remainder would stick around for the remainder of the OCI. Given this, dilution levels may not plateau at some point but could steadily increase over time, even with highway driving. As the text above the table says, some of the effects of higher evaporation temperatures are: "...increased deposits and dilution of engine oil".
I acknowledge I could have this wrong, but it is supported by my personal experience: even after a very long Interstate drive, my DI Honda still shows fuel dilution >5%. It seems to me the only real solution for owners of chronic fuel diluters is frequent oil changes.
Thoughts? Thanks.
