What does fuel dilution do to an engine?

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Just wondering since I have a 2.0 Eco-Boost on my '17 Ford Edge.

Also, how will I know it's affecting the engine?
 
A lot of the DI and DI turbo UOAs show fuel dilution but in most cases it doesn't appear increase wear levels - Blackstone rarely freaks out over it, unless the dilution rate is catastrophic (i.e. Bad HP fuel pump leaking into the crankcase etc). I quit worrying about wear, but I hope the oils ability to the innards clean is not compromised.
I'll bet that new Edge is nice, care to give us a review? I like bitog reviews!

Cheers!
 
Originally Posted By: double vanos
A lot of the DI and DI turbo UOAs show fuel dilution but in most cases it doesn't appear increase wear levels - Blackstone rarely freaks out over it, unless the dilution rate is catastrophic (i.e. Bad HP fuel pump leaking into the crankcase etc). I quit worrying about wear, but I hope the oils ability to the innards clean is not compromised.
I'll bet that new Edge is nice, care to give us a review? I like bitog reviews!

Cheers!


I'll do a Blackstone sample when I get my first oil change then and see if I need to worry about it.

As for the Edge, she is sweet. The ride is way smoother than my uncle's new Impala, and that think is smooth. And it handles really like a car when it comes to sharp turns and such. It's really quiet, and since it's the titanium edition the Sony soundsystem is awesome, and just as good as the Bose sysem I had in my previous vehicle (Envoy).

The only thing I don't like is that since I'm tall, the seats aren't as long as I'm used to, but the shoulder room more than makes up for it.

I'm still getting used to the way a little 2.0 turbo accelerates, namely not as fast as my old 6 cylinder did, but considering the great mileage and comfort, I don't even care honestly.

so if you're in the market for a two row mid-size CUV, you can't go wrong.
 
First, fuel dilution can reduce engine oil's viscosity considerably. It's not hard to find UOAs here where a 20 weight 100C viscosity has been reduced to around 6.0 from a starting level of 8.5-9.0. This may only matter in times of very hard use, but the viscosity issue seems the most significant fuel dilution effect. Ford changed the viscosity recommendation for many of its EcoBoost engines from 5w-20 to 5w-30 a few years ago; it seems likely this was in response to fuel dilution.

Second, gasoline isn't as good a lubricant as engine oil. In typical quantities, even with badly diluted oil, this doesn't seem to make a noticeable difference in wear, but it can't be a good thing.

Third, if dilution is bad enough crankcase levels can increase. At some point the level could get high enough to contact ththe crankshaft and aerate the oil, which could be a real problem. One supposes that an awful lot of dilution would have to be present for this to happen but it's not impossible.

A UOA could be helpful in identifying the extent of fuel dilution. But if you want a real dilution level avoid Blackstone: they infer a value based on an observation of flashpoint and this method has been widely discredited here. Labs that use gas chromotography (Polaris is one) measure dilution directly. If you do use Blackstone, ignore the reported fuel dilution value and focus on 100C viscosity.

Or, you could join the very large "don't worry, be happy" crowd and pretend you've never heard of fuel dilution. This may not be the worst course of action...
 
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The 2008 Mazdaspeed3 I owned was a notorious Gas diluter. This early DI turbo (designed in the early 2000s) made great power (116hp/liter) but was very hard on oil. Oil would turn black in 1000 miles. You could get a strong smell of gas by pulling the dip stick. Blackstone tests at 3000 miles showed 2.5-3.0 levels. The solution was to change oil by 2500-3000 miles.
 
The biggest impact of fuel dilution that can harm an engine is a reduction in the oil film thickness (OFT). Bearings require a certain amount of OFT to operate and maintain lubrication between the parts. We can guestimate the OFT change by looking at the viscosity but this does not take into account the design of the engine. Often on these boards I see people say the oil weight went out of grade... we don't know if this matters or not. The engine was designed with OFT in mind and the viscosity just happens to follow.

FWIW: If my past jobs in engine development 5% was a typical level where we became worried about fuel dilution. Never did we point to viscosity and get concerned.
 
It doesn't directly do much, but it does dilute the engine oil causing it to thin, usually fuel dilution won't do any catastrophic damage unless it dilutes the oil to the point that the oil becomes too thin to lubricate the engine properly.
Ecoboost engines are known to be pronte to diluting the oil, like most if not all direct injection gasoline engines, so oil selection is a bit more important than the average naturally aspirated port injection gasoline engine.
 
Questions to go along with this, is short tripping the problem and does getting oil up to temp and keeping it there (nice 1+ hour drive on the freeway and such) do enough to "burn off" the excess fuel and reduce the dilution problem?
 
Originally Posted By: FordCapriDriver
It doesn't directly do much, but it does dilute the engine oil causing it to thin, usually fuel dilution won't do any catastrophic damage unless it dilutes the oil to the point that the oil becomes too thin to lubricate the engine properly.
Ecoboost engines are known to be pronte to diluting the oil, like most if not all direct injection gasoline engines, so oil selection is a bit more important than the average naturally aspirated port injection gasoline engine.


So which oil would be better at not thinning out? Is that why they recommend a synthetic blend? Would a full synthetic reduce the oil thinning even better?
 
Originally Posted By: blupupher
does getting oil up to temp and keeping it there (nice 1+ hour drive on the freeway and such) do enough to "burn off" the excess fuel and reduce the dilution problem?


There always seem to be just "a little left behind" that doesn't "boil away"
 
Originally Posted By: AnarchyX
Originally Posted By: FordCapriDriver
It doesn't directly do much, but it does dilute the engine oil causing it to thin, usually fuel dilution won't do any catastrophic damage unless it dilutes the oil to the point that the oil becomes too thin to lubricate the engine properly.
Ecoboost engines are known to be pronte to diluting the oil, like most if not all direct injection gasoline engines, so oil selection is a bit more important than the average naturally aspirated port injection gasoline engine.


So which oil would be better at not thinning out? Is that why they recommend a synthetic blend? Would a full synthetic reduce the oil thinning even better?

Castrol Magnatec 5W-30 has been shown to work great in Ecoboost engines.
 
Originally Posted By: blupupher
Questions to go along with this, is short tripping the problem and does getting oil up to temp and keeping it there (nice 1+ hour drive on the freeway and such) do enough to "burn off" the excess fuel and reduce the dilution problem?


Short tripping is not the only problem. Depending on how aggressively an OEM decides to tune, dilution can occur even with highway-only driving, presumably because the mixture is richened to avoid LSPI and pre-ignition. My na DI Honda dilutes quite a bit with Interstate-only driving, for instance.

And once fuel gets into the sump a large portion will remain. Gasoline's lighter elements will boil off at normal oil temps, but the heavier elements won't. If Michigan's gasoline volatility guide is correct, about 1/2 of gasoline in will remain, even if no more is added.

But some OEMs handle fuel dilution well, so none of this may apply to your situation.
 
In one of my former jobs, one(of the many) things I did was test oil samples on internal combustion reciprocating engines. We sampled these engines daily, at least, and sometimes more often. One of the concerns on a viscosity test is this: IF you have oxidation AND fuel dilution at the same time, there is a POSSIBILITY of being okay on vicosity (i.e. testing within the standards for new in that type of oil), which also means sump levels are possibly okay. But what you have is fuel diluted oxidized oil. Fuel dilution is not good, no matter what. Now the question, is in this day and age, does it matter that much? The oils these days are much better at controlling less than ideal situations. My wife and I just bought two new F-150 2.7 ecoboosts in the past few months. We came from a 2013 F-150 5.0 and a 2014 Ford Edge 3.5, both naturally aspirated. These new vehicles are the first modern DI turbo vehicles we have owned. I was (almost) stunned, when after a couple hundred miles on both, I pulled the dipstick on both and noticed a strong fuel smell and a dark color. It was almost like being back in the early '80's!
I have given this a lot of thought, with a lot of considerations:

1). Part of the benefit of owning a new vehicle is that they have a warranty. I have been through warranty issues before. If the dealer you are claiming the warranty with has done the maintenance (oil changes), then they are much more likely to expedite issues. I don't give a [censored] about Magnuson Moss, etc. Technically that is true, but not realistically. Therefore, for $40+ bucks a pop, the Ford dealer will change the oil and filter, rotate tires, etc. After a couple initial oil changes at closer intervals, I am going to have this done every 5k miles. In between, every 2500 miles, clandestinely, I am going to dump the sump oil (no filter change), and put a new 5-ish quarts in of the same Motorcraft 5W-30. I am going to send samples of this 2500 mile oil off to see how we are doing. I have no problem with Blackstone's flashpoint test. It may not be as exact as a chromatograph, but it is a decent indicator.
2}. A lot of people think that this fuel dilution and oil darkening in the turbo DI engines is okay. It may turn out to be not a huge deal, but that oil is not in as good a shape as, say, the oil on my 2014 Edge, after the same miles. Anyone that says it is okay is full of _____. I think my regimen listed in 1) is a decent, not super expensive way to minimize complications.
 
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Originally Posted By: bigj_16
In one of my former jobs, one(of the many) things I did was test oil samples on internal combustion reciprocating engines. We sampled these engines daily, at least, and sometimes more often. One of the concerns on a viscosity test is this: IF you have oxidation AND fuel dilution at the same time, there is a POSSIBILITY of being okay on vicosity (i.e. testing within the standards for new in that type of oil), which also means sump levels are possibly okay. But what you have is fuel diluted oxidized oil. Fuel dilution is not good, no matter what. Now the question, is in this day and age, does it matter that much? The oils these days are much better at controlling less than ideal situations. My wife and I just bought two new F-150 2.7 ecoboosts in the past few months. We came from a 2013 F-150 5.0 and a 2014 Ford Edge 3.5, both naturally aspirated. These new vehicles are the first modern DI turbo vehicles we have owned. I was (almost) stunned, when after a couple hundred miles on both, I pulled the dipstick on both and noticed a strong fuel smell and a dark color. It was almost like being back in the early '80's!
I have given this a lot of thought, with a lot of considerations:

1). Part of the benefit of owning a new vehicle is that they have a warranty. I have been through warranty issues before. If the dealer you are claiming the warranty with has done the maintenance (oil changes), then they are much more likely to expedite issues. I don't give a [censored] about Magnuson Moss, etc. Technically that is true, but not realistically. Therefore, for $40+ bucks a pop, the Ford dealer will change the oil and filter, rotate tires, etc. After a couple initial oil changes at closer intervals, I am going to have this done every 5k miles. In between, every 2500 miles, clandestinely, I am going to dump the sump oil (no filter change), and put a new 5-ish quarts in of the same Motorcraft 5W-30. I am going to send samples of this 2500 mile oil off to see how we are doing. I have no problem with Blackstone's flashpoint test. It may not be as exact as a chromatograph, but it is a decent indicator.
2}. A lot of people think that this fuel dilution and oil darkening in the turbo DI engines is okay. It may turn out to be not a huge deal, but that oil is not in as good a shape as, say, the oil on my 2014 Edge, after the same miles. Anyone that says it is okay is full of _____. I think my regimen listed in 1) is a decent, not super expensive way to minimize complications.

DI Gasoline engines do create more soot than port injection engines so i would not worry.
 
My 1977 Caddy DeVille wiped an engine bearing due to fuel dilution around 1991. Actually, it was a fuel pump diaphragm failure that allowed pints/quarts of fuel to get into the engine oil. I saw the gas gauge visibly dropping over less than a minute as the gas poured into the engine. Before I could exit the highway the "knock knock" sound was there. [censored] fuel pump/engine design to allow that happen.
 
Originally Posted By: FordCapriDriver
Originally Posted By: bigj_16
In one of my former jobs, one(of the many) things I did was test oil samples on internal combustion reciprocating engines. We sampled these engines daily, at least, and sometimes more often. One of the concerns on a viscosity test is this: IF you have oxidation AND fuel dilution at the same time, there is a POSSIBILITY of being okay on vicosity (i.e. testing within the standards for new in that type of oil), which also means sump levels are possibly okay. But what you have is fuel diluted oxidized oil. Fuel dilution is not good, no matter what. Now the question, is in this day and age, does it matter that much? The oils these days are much better at controlling less than ideal situations. My wife and I just bought two new F-150 2.7 ecoboosts in the past few months. We came from a 2013 F-150 5.0 and a 2014 Ford Edge 3.5, both naturally aspirated. These new vehicles are the first modern DI turbo vehicles we have owned. I was (almost) stunned, when after a couple hundred miles on both, I pulled the dipstick on both and noticed a strong fuel smell and a dark color. It was almost like being back in the early '80's!
I have given this a lot of thought, with a lot of considerations:

1). Part of the benefit of owning a new vehicle is that they have a warranty. I have been through warranty issues before. If the dealer you are claiming the warranty with has done the maintenance (oil changes), then they are much more likely to expedite issues. I don't give a [censored] about Magnuson Moss, etc. Technically that is true, but not realistically. Therefore, for $40+ bucks a pop, the Ford dealer will change the oil and filter, rotate tires, etc. After a couple initial oil changes at closer intervals, I am going to have this done every 5k miles. In between, every 2500 miles, clandestinely, I am going to dump the sump oil (no filter change), and put a new 5-ish quarts in of the same Motorcraft 5W-30. I am going to send samples of this 2500 mile oil off to see how we are doing. I have no problem with Blackstone's flashpoint test. It may not be as exact as a chromatograph, but it is a decent indicator.
2}. A lot of people think that this fuel dilution and oil darkening in the turbo DI engines is okay. It may turn out to be not a huge deal, but that oil is not in as good a shape as, say, the oil on my 2014 Edge, after the same miles. Anyone that says it is okay is full of _____. I think my regimen listed in 1) is a decent, not super expensive way to minimize complications.

DI Gasoline engines do create more soot than port injection engines so i would not worry.


Well, except, for example, I think soot was the reason for premature timing chain failures on GM DI V-6s. This prompted a fairly dramatic reprogramming of the oil life monitors on these engines. So soot doesn't seem to be a particularly benign addition to motor oil.,
 
Originally Posted By: AnarchyX
Originally Posted By: FordCapriDriver
It doesn't directly do much, but it does dilute the engine oil causing it to thin, usually fuel dilution won't do any catastrophic damage unless it dilutes the oil to the point that the oil becomes too thin to lubricate the engine properly.
Ecoboost engines are known to be pronte to diluting the oil, like most if not all direct injection gasoline engines, so oil selection is a bit more important than the average naturally aspirated port injection gasoline engine.


So which oil would be better at not thinning out? Is that why they recommend a synthetic blend? Would a full synthetic reduce the oil thinning even better?


If oil gets into the sump, every oil, synthetic, blend or conventional, will thin by a similar amount. If that's a concern, using an oil that falls on the higher side of the viscosity range may be beneficial. Typically, Castrol and Mobil1 are nearer the top of a viscosity range than Pennzoil, for example.
 
Originally Posted By: SilverFusion2010
Might be time for a 10w-30 HDEO in DI Turbos. Those oils already are designed to protect and deal with soot


Can you give an example of one?
 
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