2016 Ford F-350 Crew Cab LWB Dually 6.7 Mileage

[Texas_Roadrunn1]

Our 6.7 liter truck mileage has dropped from the 14-16 mpg range on the highway to around 12-13 mpg when not towing. Truck has about 35,000 miles on it. We have seen mileage in town as low as 10.5 mpg. We have a K&N air filter which has been recently cleaned and we have added Power Service Diesel Kleen Injector Cleaner and Performance Improver to our last tank of fuel without any improvement. Has anyone had similar experience with the Ford 6.7 liter diesel. If so, what was your resolution? Our dealer doesn't seem to want to confront the issue. Thanks in advance for your help.

[FishOnOne]

ppine wrote:
A new air cleaner is the cheapest way to improve your mileage with a diesel.

I drove a calm trip last weekend to the deercamp and made a solid 21mpg. Been doing this for the last 137k miles.

[FishOnOne]

Chuck .. wrote:
I am writing to learn, not to push any product or name brand. I am not a salesman of any product.

I personally have had good luck with Amsoil Products for many years. Said this, does not mean I can not learn from others and or find possible better products.

Tell us all your opinion and experiences.

I've had extremely good luck with Mobil Delvac, Shell Rotella, and Ford Motorcraft oils. Never a problem with off the shelf motor oils running my two Ford diesels collectively >300k miles using the oils listed.

[ppine]

A new air cleaner is the cheapest way to improve your mileage with a diesel.

[Cummins12V98]

Chuck .. wrote:
I am writing to learn, not to push any product or name brand. I am not a salesman of any product.

I personally have had good luck with Amsoil Products for many years. Said this, does not mean I can not learn from others and or find possible better products.

Tell us all your opinion and experiences.

Stick with AMZ/OIL.

[Chuck___]

I am writing to learn, not to push any product or name brand. I am not a salesman of any product.

I personally have had good luck with Amsoil Products for many years. Said this, does not mean I can not learn from others and or find possible better products.

Tell us all your opinion and experiences.

[deltabravo]

Get rid of the K&N filter.

[Cummins12V98]

Good deal dropping the K&N

[Texas_Roadrunn1]

Thank you all for your replies. While DH is off on a hunting trip, returned loaner on his way south and picked up truck, don't know how it is performing. Will be anxious to see how it does mpg wise. He did tell me that the dealership, Ancira in Floresville, for you guys who live around here, said there was nothing wrong. He had also asked them to change oil and transmission fluid, neither of which had been done. They had had the truck four days! Go figure! Will have him read the latest replies to see if we can get any improvement if we implement any of the suggestions. He has ditched the K&N filter, which he installed at the suggestion of a friend.

[GoPackGo]

Diesel fuel starts to cloud up at about 20 degrees. So you need to have projected extended below freezing temps for there to be problems which require fuel treatment at the pump. I'm not from Texas but I'd be surprised if they do much of anything to the straight #2 in San Antonio. And if they do, they can treat with chemicals instead of adding #1 diesel. You won't know unless you ask - and expect a blank stare unless you are at a truck stop. So I don't think that's the problem here. Even if they treat with #1, I'd guess the percentage is small.

Did the MPG drop right after the air cleaner change ?

Has it thrown any codes ?

Diesels are un-throttled engines. They flow a huge amount of air. I would go back to the OEM filter system and see if MPG goes back up. When something changes, I always look back at the last thing I did - that's usually what caused the change.

If you go back to a paper filter, get the Ford one. The after market versions can collapse due to the large airflow.

I get about 14-15 mpg around town from my 2013 F350 4x4 dually. I get over 20 mpg at 55-60 mpg and about 19 mpg at 65. All non-towing.

[Cummins12V98]

FYI, AFE was started by previous K&N employees and make a much higher quality oil type filter. Even theirs are not a good idea for any vehicle with sensors. Their filtration is great compared to K&N.

[Bird_Freak]

You need to lose the K&N and put the stock filter back in. It flows more air than the K&N.

[JeremyFr]

Agreed with everyone else get rid of the crappy "cleanable" filters, there is more than enough scientific proof and studies to prove all they do is gum up your sensors, screw your mileage and let far more dirt in your engine than a good paper pleated filter. I'm not a diesel guy but once you get rid of the K&N clean any sensors you may have in the intake and clean em well, might want to clean the throttle body as well afterwords no doubt you'll find them both all gummed up with ****.

[drsteve]

larry barnhart wrote:
we had an K&N filter on our 8.1 chev and it didn't let the dogs out but let the dirt in. Very surprised what we saw in the intake tube.

chevman

That's how they let more air in--by not filtering it as well. K&N filters are junk, IMHO.

[cummins2014]

ppine wrote:
I have a big heavy F-350 with the 7.3. It gets 20-23.8 mpg empty.
My uncle Alaska Bob was a diesel mechanic for decades. He taught me the importance of getting air in and out of a diesel engine. After market air intakes (not just a different filter) and a new larger 4 inch exhaust system make a big difference.

The head pipe on my stock exhaust was 3 inch in diameter except there was a 90 degree bend that flattened the pipe. Replacing it with an after market 4 inch pipe that is totally round changed the performance of the truck.

Well thats a pretty exceptional 7.3. I too spent nearly 16 years with a 7.3 Superduty 350.

I too went 4" turbo back, AIS intake , DP tuner etc etc ect, and cracked 20 mpg, JUST once on a pretty flat secondary road at 55 mph. The rest of the time 16-18 empty at freeway speeds.