coborn35

Picked my 2012 FX4 Screw roughly a month ago from a dealer. When I got in the mileage calculator was around 14.5. I didn't think anything of it, was in the honeymoon phase. Started consistently getting around 13 MPG which is horrible. Couldn't figure out why. I went in to have the oil changed and the mechanic calls me over and asks when I last had my oil changed. Apparently it stunk bad like gas and it looked like some had been getting into the oil. (SIDENOTE after poking around and looking it appears that these DI engines will do that and its not that big of a deal if you look after it?) They found a sticker hidden on the window that indicated the truck was about 3,000 overdue for an oil change (not my fault and the truck indicator had just hit around 5% life). I had a hunch so I reset my fuel calculator and filled up. I just took about a 900 mile roundtrip which included highway and city/backwoods driving and I currently sit at 18.5 MPG for the trip (got 20 MPG highway). I left Trip A where it was, it had about 200 miles averaging 10.1 MPG. Within 50 miles of driving it had jumped all the way up to 18 MPG. It appears that gas getting into the oil was enough to drastically mess up my mileage. It sounds as long as I get my oil changed religiously between 3,000 and 5,000 miles this gas thing shouldn't be a major concern, but again thats just off google.

Tothemax

All di engines will put small amounts of fuel into the oil. You have to watch the ecoboost as guys have issues with more than normal levels show up in their oil. Could be a faulty HPFP, could be lots of short trips in the winter, could also be a few other things.

I have a hard time seeing a 5.5mpg gain from an oil change. Sounds more like a driving habit change but whatever. As long as your happy.

Heel70

As a side note this is why I'm not going to trust the oil life monitoring on these trucks or any vehicle for that matter that is based on driving style alone. I change my oil and filter every 5k regardless. Some might say I'm crazy and wasting money but i'm not going to go 8 or 10k miles or more in between oil changes.

PARIAH

Coborn

Idling in winter will add fuel to the oil. Had that issue and Ford did a TSB on it. That repair did ammount to a reduction but not elimitation of the problem. If it's really troubling a catch can may be in your future.

coborn35

I don't know how I would change my driving habits over the course of a day?

Atlee

Agree. I try to always change oil at 5K and change. Doesn't hurt to have fresh oil in the engine. And neither do I wait for the oil monitor tell me it's time to change oil.

DavidKR

I change my oil at 3-4000 and spark plugs and air filter every 10k. it may be overkill but I'm getting 21-22 highway with 35s so I'm not about to start doing anything differently haha.

Tothemax

How many miles did you go to get that mileage number? I can drive super conservatively to get 20ish MPGs. Also, weather conditions factor in.

Im just saying, changing your oil isnt going to increase your mileage by that much, Plus you need to drive the truck longer than a day to get an accurate reading.

JLTD

I agree that a more accurate assessment will be had after a bit more mileage following the oil change; that said, there IS increased wear in an engine with heavy fuel dilution due to increased friction [insert long oil nerd discussion here about chemistry...bobistheoilguy.com styel] so it certainly is possible that the mpg has jumped up.

DI's fuel dilution is one reason I went with the 5.0; both are great engines but the Eco requires more frequent oil changes; 5k sounds like a good interval.

Coborn35, at least you have a backup oil change alert system - when your mpg takes a dive it's past due!

HacksawMark

Only just a little.....