Theory on fuel in oil.

[Grady]

Fuel in oil happens on all piston engines. Fuel evaporates at low temperature so normal driving with the oil at temperature will get the fuel to evaporate off. Way back on large radial aircraft engines they had a fuel dilution valve to put fuel into the oil on shutdown in cold climates. This kept the oil from being to thick on startup after sitting at below 0 temperatures. On the next flight the fuel would evaporate off. by doing this you just needed to change the oil more often. Ok back to our engines. I have put a M catch can on my truck and after a couple of thousand miles noticed it is full of mostly a fuel smell thin liquid and a little water. So the catch can is catching some/most/all? of the fuel that is being evaporated off.

Now my theory on why and possibly a way to check. Fuel dilution is common on diesel engines, if you compare our engines in normal driving the RPM’s are similar. Shifting just after 2k and wanting to cruse below 2k. At this speed scavenging will not be as efficient and cylinder pressures will be higher. My plan is to do 2 different tests of the same milage. One will be in normal where the RPM will be kept in it normal range. The 2nd will be in S. I will keep cruse RPM at least 2.5k, more in the normal for a 4 cylinder car. This may take me a while I only drive the truck to work 3 times a week or so.

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[Grady]

Ok did just over 1k miles in S mode thought that would be a good start point. With the Oz tune shifting was 3k plus even on light throttle. On the highway I would lock into 8 to keep RPM’s around 2.5k. I live in Dallas so just under 50% of the time for highway miles. I did not have a good cup for testing but this was the result. Some oil, some water, seemed like mostly gas.

 

[Grady]

Got the 2nd 1k miles. took way to long. One issue is since it took a while one control that changed dramatically that I think had the biggest factor was OAT. The first 1k was done with cold OAT. This one probably the average OAT was over 90 deg. less in the catch can but that could be attributed to a quicker evaporation rate of the fuel.

 

[Wytchdctr]

I blame ASS (with zero evidence of why or how)

 

[Grady]

I blame ASS (with zero evidence of why or how)

That is eliminated from the test. I have auto start stop Eliminator.

 

[Wytchdctr]

That is eliminated from the test. I have auto start stop Eliminator.

Stupid post aside i'd be curious to see if it really has an impact. Idling vs starting all the time.

 

[KNI]

I vote for stuck piston ring (with zero evidence of why or how).

 

[D Fresh]

You might be on to something. The tendency of this engine to lug a bit could definitely contribute to the issue.

That could also explain why those who flog the truck regularly aren't seeing these problems.

 

[MotoWojo]

I believe i have this problem worse than most and I have driven 20,000+ miles with it. I'll spare most of the background, but will note Ford replaced the HPFP, all 4 injectors twice, the oil separator system, and all high pressure fuel lines with no improvement. Compression and leak-down tests were done several times and all were within spec. My fuel dilution tests have all been taken by the dealership and one by Ford, 12% after 500 miles driven on the oil was the lowest. Over a dozen oil changes in that time. I drive 50 miles round trip to work, 5 days a week and live in the sticks, so no short drives for me. This problem did not start until 7,000+ miles on the truck. For my truck, 250 - 500 miles after an oil change, the oil level was above the max hole, and eventually would get to about 3/8in over the twist and stay there. I checked my oil pretty much every morning, after the truck has sit overnight as to get a good comparative reading.

During this time I tried several different driving styles, from oil change to oil change, to see if it got better or worse.

1. I drove solely in sport mode and spirited as much as I could without becoming a hooligan.
2. Using the Torque app, I monitored boost, and manually shifted to try to stay out of boost.
3. I locked out 10th gear pretty much all the time.
4. I drove as light pedaled as I could stand, hypermiling.

None of this made a difference. Ford finally just told me that they concluded that it is just the nature of this engine/vehicle combination, that it was not harming the engine, and that they would no longer do anymore warranty work related to the rising oil level. I asked them if I still had to check the oil level, and they told me yes, I then asked what level should I consider it a problem, and they said they would get back to me. They never did. They did however offer to extend my powertrain warranty to 7yrs/1000,00, which I took. I plan on just doing 7,500 mile oil changes and see how long it lasts. If it is still running at 99,000miles, it will be traded in on something else. Besides all the problems I am having with this truck, I really do like the design and it fit's what I want. I think I just got a lemon.

 

[kieefer]

I believe i have this problem worse than most and I have driven 20,000+ miles with it. I'll spare most of the background, but will note Ford replaced the HPFP, all 4 injectors twice, the oil separator system, and all high pressure fuel lines with no improvement. Compression and leak-down tests were done several times and all were within spec. My fuel dilution tests have all been taken by the dealership and one by Ford, 12% after 500 miles driven on the oil was the lowest. Over a dozen oil changes in that time. I drive 50 miles round trip to work, 5 days a week and live in the sticks, so no short drives for me. This problem did not start until 7,000+ miles on the truck. For my truck, 250 - 500 miles after an oil change, the oil level was above the max hole, and eventually would get to about 3/8in over the twist and stay there. I checked my oil pretty much every morning, after the truck has sit overnight as to get a good comparative reading.

During this time I tried several different driving styles, from oil change to oil change, to see if it got better or worse.

1. I drove solely in sport mode and spirited as much as I could without becoming a hooligan.
2. Using the Torque app, I monitored boost, and manually shifted to try to stay out of boost.
3. I locked out 10th gear pretty much all the time.
4. I drove as light pedaled as I could stand, hypermiling.

None of this made a difference. Ford finally just told me that they concluded that it is just the nature of this engine/vehicle combination, that it was not harming the engine, and that they would no longer do anymore warranty work related to the rising oil level. I asked them if I still had to check the oil level, and they told me yes, I then asked what level should I consider it a problem, and they said they would get back to me. They never did. They did however offer to extend my powertrain warranty to 7yrs/1000,00, which I took. I plan on just doing 7,500 mile oil changes and see how long it lasts. If it is still running at 99,000miles, it will be traded in on something else. Besides all the problems I am having with this truck, I really do like the design and it fit's what I want. I think I just got a lemon.

I would change the oil according to the dash read out, say at 10% but that’s me.
Thanks, first good dealer service explanation I’ve found.
It appears some engines have this issue and some don’t, like mine, it has other issues but not the excessive gas in oil problems.
Good luck.

 

[McLeadslinger]

I don’t beat on my truck much but it’s tuned and I have very little if any dilution or fuel/oil blow by.

Those that drive like grandpas just so they can brag about fuel economy could be creating the problem by not letting the motor work. These motors like RPM.

 

[MotoWojo]

I don’t beat on my truck much but it’s tuned and I have very little if any dilution or fuel/oil blow by.

Those that drive like grandpas just so they can brag about fuel economy could be creating the problem by not letting the motor work. These motors like RPM.

From my post earlier, I tried several different driving styles, and it did not make a difference if I drove it "like I stole it" or if I drove it "like a little old lady on her way to church". In fact it did not make much difference if it was hot or cold out, although the oil level did seem to climb a little slower during the summer months. If you don't have the issue, I believe you are in the fortunate majority, and I don't think it has anything to do with how the truck is driven, as long as the engine gets up to temperature?

 

[Cabose-1]

I have posted the reason as to why there is fuel in the oil. I will post again.

Direct injection engines
They build carbon on the intake valve
Since oil goes over the intake valve, have some fuel in it
Like an old fashioned intake, now you have fuel going over the vavles to help keep it clean,
Like a more traditional engine.

Brilliant!
Science at work

 

[Doc]

I believe i have this problem worse than most and I have driven 20,000+ miles with it. I'll spare most of the background, but will note Ford replaced the HPFP, all 4 injectors twice, the oil separator system, and all high pressure fuel lines with no improvement. Compression and leak-down tests were done several times and all were within spec. My fuel dilution tests have all been taken by the dealership and one by Ford, 12% after 500 miles driven on the oil was the lowest. Over a dozen oil changes in that time. I drive 50 miles round trip to work, 5 days a week and live in the sticks, so no short drives for me. This problem did not start until 7,000+ miles on the truck. For my truck, 250 - 500 miles after an oil change, the oil level was above the max hole, and eventually would get to about 3/8in over the twist and stay there. I checked my oil pretty much every morning, after the truck has sit overnight as to get a good comparative reading.

During this time I tried several different driving styles, from oil change to oil change, to see if it got better or worse.

1. I drove solely in sport mode and spirited as much as I could without becoming a hooligan.
2. Using the Torque app, I monitored boost, and manually shifted to try to stay out of boost.
3. I locked out 10th gear pretty much all the time.
4. I drove as light pedaled as I could stand, hypermiling.

None of this made a difference. Ford finally just told me that they concluded that it is just the nature of this engine/vehicle combination, that it was not harming the engine, and that they would no longer do anymore warranty work related to the rising oil level. I asked them if I still had to check the oil level, and they told me yes, I then asked what level should I consider it a problem, and they said they would get back to me. They never did. They did however offer to extend my powertrain warranty to 7yrs/1000,00, which I took. I plan on just doing 7,500 mile oil changes and see how long it lasts. If it is still running at 99,000miles, it will be traded in on something else. Besides all the problems I am having with this truck, I really do like the design and it fit's what I want. I think I just got a lemon.

2.”Using the Torque app, I monitored boost, and manually shifted to try to stay out of boost.”

Why stay out of boost ?

 

[Joeiconic]

Reserved for sarcastic remarks.

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