o'k, update! I'm not sure this makes sense to anyone but it IS what seems to be going on. The dealer couldn't get it in until the 23rd. Another story altogether. Anyhow I have had unbelievable results from SeaFoam Motor treatment over the yrs, both in out and fuel. Wanted some for ATV, also dumped maybe 1/4 can that's what 4 ozs? Like I said the tail pipe went from spotless inside up to 1500 miles to Coal black @ 2200 miles. you rub your finger in the pipe it was as black k as it would be from inside a wood stove!! After SeaFoam I noticed the other day the pipe has gone from Black to light grey! Jury is out on furl mileage but I bet it's better. Why???? I'll let you all guess, what do I think?? crap in fuel system from bad gas!!! I don't really care why long as it's o'k now.

 

Maybe Ford is controlling the engine computer by satellite
lol

 

Never thought of that!!! Nothing would surprise me!!!

 

gas is probably controlled through your computer by satellite

 

No Actually I doubt it since I put a lead shield around the computer!!!!!!! Now you believe that I'll come up with a new one!!!

 

Sounds exactly like bad gas. Probably the computer was trying to compensate for it. When the tailpipe turned black, were you towing? Ford says 87 octane for normal driving, but suggests 91/92 octane for towing. If you were towing, the computer could have been dumping gas to help with the towing

 

to be honest I kinda wondered about bad gas.

 

You know its funny how things change. Years ago I hauled gasoline for 4-5 yrs or so. Worked for an independent oil/gas company in Maine. We hauled out of Mobil, Exxon, Shell, Amoco, Texaco and a few others. From So. Portland Maine, Newington N.H., East Boston. That was back in the days of allocation, which many off you remember nothing of. Each month we hauled every drop the cheapest one for that month allows...and then some until they shut us off. Then on to the next. I hauled Mobil gas into Texaco, Shell, amoco whatever stations! I'd listen to people say "I won't buy a drop of this or that and LMAO!
Most independents have been taken over by the big boys today. There IS such a thing as bad gas today, also sometimes the gas is only as good as the dealers take care of their tanks at the station. There have been times in the last couple yrs where I have thought Shell might give me a little better mileage but probably all in my old worn out head!!

Also I wasn't aware Ford suggests better grade for towing but I have noticed better power and mileage with 89 or 93...or thought I did!! Maybe my old worn out head works better than I thought!!! Thanks everyone for you advice...any idea what will happen when I put that big ol turbo out there on this 7.3 that boosts the hp to over 700 hp and ungodly torque??

 

Check this out. Supercharged 7.3L towing a 10K trailer. What MPG Can the New Supercharged 7.3L Ford Super Duty Get? You Asked, Here It Is! - The Fast Lane Truck (tfltruck.com)

 

Exactly right about how the dealers take care of their tanks. When I lived in International Falls, MN, a friend who owned a station would dip his tanks every day using a signal dye on the stick to indicate water in the tank. Two other stations used electronic measurement (in tank sensors) and consistently had water issues, especially with the diesel. One went to the stick and dye while the other just kept pumping away. The later had to shut down for a few days while the tanks were emptied, cleaned, recertifed and fresh fuel purchased and filled. 6 months later, repeat. It pays to know who you buy your fuel from, though that can be very difficult on cross country trips.

 

Interesting! My new 5th wheel weighs10,000 lbs empty but definitely tows easier than that trailer in the video. I can't tow 60-65 on the highway, sorry just can't take it!!The first 90 miles from the dealer was not highway, we were restricted to about 60-65 and I was very pleased to get 9-9.5 like I say averaging 60-65!! The "bumper" hitch travel trailer I hauled up there to trade weighed about 6000lbs, 4000 lbs lighter than the 5th wheel and on same rd, same speed/conditionsgot AROUND 7 mpg! So yes the 5th wheel does tow easier, part of that is aero and the fact the 5th wheel is 2' behind the truck cab.....drafting the truck!

 

I know this is kinda old but my recently purchased 2022 was getting 19 give or take on the highway with 37’s on 24’s and about 12 in town.

now I’m lucky to get 10.5 in town and 15 on the highway. Driving habits have not changed and even switched to eco drive mode. Forgot to mention it’s a 6.7.

i got the truck with 9300 miles and now it has 11348. This changed within the last 600 miles. I baby the hell out of it and like I said I have not changed the way I drive it. Do t drive with a heavy foot at all. It’s funny bc when I first got it I hooked on to my 19’ aluminum boat bc I’ve never owned a diesel one just to see how much better it was then my f150 5.4 3v supercharged and I was getting 14.8 pulling it. I’ve checked the dash numbers with hard numbers and it’s almost on the money.

the only thing that has changed is i put a little more air in my tires. That’s it. I keep it with a fuel tank also. I hate to bring it in but it’s gotta get better with these fuel prices.

 

cant speak from experience on the 6.7 as mine (2020) is the 7.3. Sometimes I think my mileage has slipped, well in fact I KNOW it has. I'm at 23,000 miles. Of coarse you have winter fuel and summer fuel...that DOES make a difference. I also do not understand the coal black tail pipe, mine and every one I have seen (7.3) is black. Where I came from a black sooty tail pipe was a rich burning engine. I thought the electronic ignitions etc were supposed to burn cleaner??
Anyhow in actuality I am more than likely unknowingly driving less efficiently now that the newness of the truck has worn off. you did not say what gears you are running. Those bigger tires more than likely will give a little better mileage on the highway and worse in town. I would say your mileage today, especially around town. But hey, mileage is not the problem, they're big trucks, the problem is the ridiculous price of fuel.