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I have a new 2018 3.5 EcoBoost F150 supercrew 10 speed. It is 100% stock

I completed the first oil change earlier than recommended at 4000 kilometers (about 2500 miles). The IOLM was still showing 80% oil life remaining, but I wanted to do an early oil change to eliminate break in metals, & was more concerned over the darkening of the oil on the dipstick.

I sent an oil analysis into Fluidlife in Edmonton, & it came back at 8.47% fuel dilution!

After discovering this I have been changing my oil at the same 4000 kilometer (2500 mile) interval, and each oil change has had fuel dilution higher than the recommended safe levels of 2%

Last oil analysis was at 4%, & the previous one was at 3.4%

I understand that these EcoBoost engines are prone to some levels of fuel dilution, but at these early oil change intervals, they shouldn't be this high.

I have been using synthetic oil.
I have contacted the salesman that sold be the truck, & the service adviser, & they don't seem to be too concerned, & wont even look at it unless it throws a "Check Engine Light" code.
I recently had it in for the Seatbelt/ duct tape recall, & another issue with the Passenger side tow mirror clearance lamp not working.

I asked them about my fuel in oil concerns, & they wont even log it on the service invoice. How do I document it with the dealer if they wont log it?

I have noticed traces of oil in the intercooler hoses, & have been watching the oil level on the dipstick closer now, & it seems to be sitting at a constant level. Maybe it has corrected itself / rings have seated, but thinking maybe the engine is pulling enough vapor/ fumes / oil through the PCV system, & intercooler to keep the fluid level at a constant level. I am going to run a little longer oil change interval this time, & send in another sample for analysis to see if it is under control (less than 2%)

I have thought about adding a "oil catch can" but not sure if they have figured out how to pull from the drivers side of the 2018 without throwing a check engine light code.

I have been reading about earlier models with the 3.5 having issue with the High Pressure Fuel Pump leaking internally into the crankcase.
Is this still an issue with some 2018 models?
Is there anything I can check myself with engine diagnostic equipment such as fuel trim levels, etc?
Should I disconnect my battery, & try a "re-learn" process?

Worried that with cooler temperatures now, that I will start to see even higher levels of fuel dilution. I don't do much city driving, or any extended idling time. I don't do short trips under 30 kilometers driving to work, so engine is always up to operating temperatures.

See the attached oil analysis reports.


1,123 Posts
Unfortunately, most service manglers at a dealership don't even know what "fuel dilution" is. You'd have to get to someone with a serious clue, or an engineer, to help with that. I would call Ford customer service.

As far as what you've tried:
Synthetic oil - this will provide better lubrication, but fuel dilution is fuel dilution... the type and weight of oil won't change the percentage dilution
Catch can - won't help
Re-learn - won't help

I've never heard of the HPFP leak, but I would suspect something like that, or an injector that's hanging open.

Sadly, the way to address this issue may be to just keep driving the truck, changing the oil when indicated by the IOLM (ideally at the dealer), and allow it to fail. At that level of fuel dilution, you should start causing premature engine wear quickly.

93 Posts

i spent this weekend reading through this entire thread and found it to be very interesting, i have an '18 also i use Amsoil and change it every 5K for the same concerns as you have "fuel dilution" from what i understand as long as the oil doesn't break down "fuel dilution" should not hurt the motor and reading through the thread you will find once the motor breaks in it does get less and less "fuel dilution"
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