High fuel dilution (3.3%) in recent oil sample, highway driving

[ccasanova22]

Has anyone seen high fuel dilution after a recent bout of highway driving and some towing? I would think short trips would increase fuel dilution, but this was run for more highway (state-to-state) trips than any other oil change I've had, and the engine was completely up to temperature every drive >15 miles per trip, with an average trip length of 35-60 miles. I also took this cross country several times and occasionally used the truck off-road.

Does this indicate a problem with my engine, or is this normal? FWIW, my coolant level has been slowly disappearing to the point where it's beneath the "MIN" mark on the overflow tank, but there have been no leaks on the garage floor that I can find.

Thank you all for the input!

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[Dereku]

Were you in boost a lot? How many miles? Good spark plugs? Oil weight and brand? How many miles on this change? Mpgs?

Mine likes to stay at min no matter what. I can add it and a few weeks later its at min. A year later still there. I quit adding and it quit going down.

 

[Cmar]

Were you in boost a lot? How many miles? Good spark plugs? Oil weight and brand? How many miles on this change? Mpgs?

Mine likes to stay at min no matter what. I can add it and a few weeks later its at min. A year later still there. I quit adding and it quit going down.

That's funny mines the same, and it's a completely different engine, I top it up to full and it slowly goes down to minimum, no further, top it up again and the same thing happens. Like you I just stopped topping it up, and it doesn't change. Some weird Ford thing???

 

[Dereku]

That's funny mines the same, and it's a completely different engine, I top it up to full and it slowly goes down to minimum, no further, top it up again and the same thing happens. Like you I just stopped topping it up, and it doesn't change. Some weird Ford thing???

I was really concerned to he honest. Either both of our engines have an issue or its normal. Now I feel better knowing im not alone.

 

[ccasanova22]

Were you in boost a lot? How many miles? Good spark plugs? Oil weight and brand? How many miles on this change? Mpgs?

Mine likes to stay at min no matter what. I can add it and a few weeks later its at min. A year later still there. I quit adding and it quit going down.

Not sure if in boost, and I change the oil well before the OLM hits 0%, usually between 4-25%, so anywhere from 7500 to 9600 miles on oil change. This last change was closer to 9,700 miles simply due to the last trip and coming back put me right there.

Spark plugs appear to be good, I have not checked in 1/2 a year though. Oil weight is 5W-30 and the oil is Mobil 1 EP (rated for 20,000 miles).

Yes, I do tow, and yes I do off-road, but the rig is mostly highway driven and average MPG is anywhere from 20-25 depending on ratio of backroads (45-55mph) to highway (70mph) which tanks the MPG.

 

[Stevedbvik1]

Not sure if in boost, and I change the oil well before the OLM hits 0%, usually between 4-25%, so anywhere from 7500 to 9600 miles on oil change. This last change was closer to 9,700 miles simply due to the last trip and coming back put me right there.

Spark plugs appear to be good, I have not checked in 1/2 a year though. Oil weight is 5W-30 and the oil is Mobil 1 EP (rated for 20,000 miles).

Yes, I do tow, and yes I do off-road, but the rig is mostly highway driven and average MPG is anywhere from 20-25 depending on ratio of backroads (45-55mph) to highway (70mph) which tanks the MPG.

What was the temperature history of this oil life cycle? Was there any extended idle times when really cold? It doesn’t take much to make the fuel dilution raise in the cold weather. We tow heavy and off road so I change my oil at around 5000 miles. Which equates to about in the fall and spring. The spring oil samples have always been elevated and the fall ones non existent. I’ve quit checking since it’s become predictable.

 

[ccasanova22]

What was the temperature history of this oil life cycle? Was there any extended idle times when really cold? It doesn’t take much to make the fuel dilution raise in the cold weather. We tow heavy and off road so I change my oil at around 5000 miles. Which equates to about in the fall and spring. The spring oil samples have always been elevated and the fall ones non existent. I’ve quit checking since it’s become predictable.

I never idle the truck, was told it’s bad and can cause extra wear vs just letting it run for a short period, driving at low RPMs, even when towing. So I’ll let the RPMs drop, put it in gear, tow 1-2 local miles at a crawl, then get on a highway. My truck never sees 2,500+ rpm when cold.

 

[Stevedbvik1]

I never idle the truck, was told it’s bad and can cause extra wear vs just letting it run for a short period, driving at low RPMs, even when towing. So I’ll let the RPMs drop, put it in gear, tow 1-2 local miles at a crawl, then get on a highway. My truck never sees 2,500+ rpm when cold.

I would bet your next sample will be fine. Maybe next winter try to get a sample at around 5k and see what it shows.
Also how much weight are you towing and how do you keep it under 2500 rpm when towing?

 

[Dereku]

Its so low compared to the limits I would not worry about it. Winter oil changes always smell more gassy than summer changes.

 

[Grandaccess]

Has anyone seen high fuel dilution after a recent bout of highway driving and some towing? I would think short trips would increase fuel dilution, but this was run for more highway (state-to-state) trips than any other oil change I've had, and the engine was completely up to temperature every drive >15 miles per trip, with an average trip length of 35-60 miles. I also took this cross country several times and occasionally used the truck off-road.

Does this indicate a problem with my engine, or is this normal? FWIW, my coolant level has been slowly disappearing to the point where it's beneath the "MIN" mark on the overflow tank, but there have been no leaks on the garage floor that I can find.

Thank you all for the input!

everything looks like nothing to worry about?
I really should send mine in, I am going on 40k with this oil, I have changed filter once, it still looks, smells and feels good, its Amsoil, sometime this summer it should be due for a change around 50k and I am going back to Mobile One also ....
they probably wouldnt even believe I went 40k on the same oil LOL my oil level hasnt gone up or down even by a hair?
my last truck went 50k between changes and I got 283k out of that engine before the F***ING Tranny went, So if the tranny on these trucks are only good for 50k why should I change the oil?

 

[Doc]

“Don’t Kill the Patient to prove the test was right”
get another sample …

 

[ccasanova22]

I would bet your next sample will be fine. Maybe next winter try to get a sample at around 5k and see what it shows.
Also how much weight are you towing and how do you keep it under 2500 rpm when towing?

Thanks, with a 2,000lb travel trailer it will shift at 2500rpm max when crawling around town. Once it warms up I’ll get on the highway and let it rev more (when the coolant temp is at least half way). Will try to get another sample next winter.

 

[Stevedbvik1]

Thanks, with a 2,000lb travel trailer it will shift at 2500rpm max when crawling around town. Once it warms up I’ll get on the highway and let it rev more (when the coolant temp is at least half way). Will try to get another sample next winter.

That makes sense. We pull 6000lbs and there’s no way to get it moving without exceeding 2500rpm ?

 

[dtech]

That makes sense. We pull 6000lbs and there’s no way to get it moving without exceeding 2500rpm ?

what kind of mpgs are you seeing pulling that weight ? I could only manage 10.5 mpg according to the computer so it may have been even lower but was towing in colder temps and lots of inclines, speeds probably averaged 60 mph. Last summer in warmer weather saw 13 to 15 mpg doing similar speeds, and I did noticed the tranny tended to stay in lower gears in the colder weather. On level or downhill stretches I don't use tow mode and frequently was in 10th gear last summer, but hardly ever saw 10th on this past trip., I tow a 4160 lbs tt , (UVW) and pack it pretty light.

 

[Stevedbvik1]

what kind of mpgs are you seeing pulling that weight ? I could only manage 10.5 mpg according to the computer so it may have been even lower but was towing in colder temps and lots of inclines, speeds probably averaged 60 mph. Last summer in warmer weather saw 13 to 15 mpg doing similar speeds, and I did noticed the tranny tended to stay in lower gears in the colder weather. On level or downhill stretches I don't use tow mode and frequently was in 10th gear last summer, but hardly ever saw 10th on this past trip., I tow a 4160 lbs tt , (UVW) and pack it pretty light.

Usually see 10-12mpg depending on which campground we go to here in Michigan. Mostly flat but some hills hence the difference. Always use tow/haul and 60-65mph. Don’t pull much in cold weather so no input regarding that. One campground in particular is 27 miles from home and flat. If I take the back roads (55mph max) then I will see 13mpg.

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