I just bought my first diesel truck back in November. It's a 2005 F-250 with the 6.0L and the 5 spd torq-shift automatic tranny. Last weekend I drove the truck to South Carolina, about a 600 mile round trip from where I live. On the trip the truck only got 13 mpg! I wasn't towing a trailer and the truck was empty except for me and my suitcase. It's not loaded up with mods or anything, it's completly stock power wise. I'm extremely dissapointed, esspecially since a friend of mine has a 2006 F-250 identical to mine and he gets up to 21 mpg on his. Can someone tell me what can be done to improve my mileage? I'm not a lead-footed driver, and the trip was done with almost all interstate and highway driving, very little driving on backroads or stop and go. If this is the best the truck will get, I'm going to sell it and buy a F-150!

 

If I drove the trip you did I would get about 17mpg with winter fuel and around 19-20 mpg with summer fuel. and thats driving at 2,000 rpm or slightly under. When you start going over 2,000 rpm your mileage drops.

 

Well 17 is still a far cry better than 13! Actually I would have been thrilled with that! I kept the truck at about 70, and the tach read about 2,000 rpms, just like you said. Didn't top it very often unless I had to.

 

watch the boost gauge. try and keep it under 5psi you will see gains that way

 

I talked to my friend with the twin truck earlier, said I should take it to the dealership and have the computer updated, that's most likely the problem. He had it done to his last year when he replaced the EGR and it made a BIG difference he said. He also said to have the fuel filters checked/replaced as it may not have been done the last time the truck was serviced.

 

If you don't have the service records on the truck I would change all filters and fluids and do recommended flushes so that I had a base line to start with. The 6.0 is a good engine but it does require meticulous maintenance. If you skimp there it will bite you.

 

I continue to be amused by "Why is my mileage so crappy?" threads.

Reasons:

1. Driver. Swap trucks with your friend and he will get better mileage in your truck. Drive his truck, and your mileage will suck.

2. Ignorance. A lot of energy is expended by pushing air out of your truck's way. In fact, the coefficient of drag squares with doubling of speed. Just an extra 5 mph on the highway sucks a disproportionate amount of fuel. At 46 MPH on a empty two lane road, my truck got 24.8 MPG - that's hand calculated. Aerodynamic drag is MUCH lower than 65, the transmission is in 5th gear, and the engine's torque can move the truck at not much more than an up idle.

3. Compare apples to apples. I have a 2005 XL Regular Cab Powerstroke FX4. It weighs 7,280 lbs. with a Snug Top camper shell, grill guard, Hella 4000 lights and 3/4 of a tank of fuel. My friend has a 2006 XLT Crew Cab 4x4 that weighs over a thousand more pounds loaded with a bunch of stuff he should clean out of the truck. He drives with a lead foot and can easily average less than 10MPG city/highway. If the cops catch him, he could average 6 - 12 months in jail.

4 More ignorance. Terrain and wind makes a huge difference in mileage

 

To 69cj: I have the service records from the dealership I bought it from which was not a Ford dealership (A Chevy one none the less), and I don't know if everything was done that they said was when they took it in on trade. I can't prove it wasn't, but I can't prove it was. They did show me a Carfax report on it too, but again, I don't know how much I can trust those things either.

To XB70: Your reasons would be valid except for a couple points:

1. Driver- My friend and I both have similar driving styles. Plus I have drove his truck before and got the same milage on it he does, my main reason for wanting one like his.

2. Ignorance- Both of our trucks are the same. Same body style, same motor, same transmission. Both are Crew Cab, short bed, 4x4's. So his truck will displace just as much air at the same speed as mine. Plus my truck has a tonneau cover and his doesn't, so mine should get a mpg or so better than his just because I don't have the drag over the tailgate like his does.

3. Apples to Apples- Again, both my truck and my friends are similar. And in truth, his has more junk in it than mine does. Car seat, and other added junk laying in the back. Where as mine stays pretty clean and doesn't have allot of unneeded junk being carried around. Plus again, my friend and I have similar driving styles so that doesn't figure.

4. More ignorance- Consider this, I went to South Carolina, over mostly flat ground, no moutains to climb or anything. This same weekend my friend took his truck, and family, to West Virginia on a ski trip. He had more people and more luggage, and had to go up and down over the mountains and still got 21 mpg.

I wouldn't be griping if the truck got 17 or 18 mpg's to his 20-21 because that would account for driving styles, extra weight etc., etc. But 13 vs. 21, that's a big difference, and I am simply trying to figure out if there is something wrong with the truck, and if anyone else out there had experienced a similar issue, and what they did. It just seemed strange to me considering I had always thought diesel trucks got exceptional highway fuel milage, which was one of the reasons I bought the truck (in addition to needing something to pull my project truck). I guess the true test will come when I take the truck to the Ford dealership and they check it over.

 

My truck is stock other than a coolant filter. I have the latest strategy updates, filters changed regularly, EGR cleaned, etc., etc. .... and I only average 13-14 MPG. It's a big, heavy truck.

I don't know how these folk claim 20+ MPG on a regular basis. Maybe this guy has tunes / chipped?

EDIT ... I have a 3.73 axle

 

Big Red,

does your friend add Cetane boost?
transfer case or front hubs stuck in 4x4?
different gear ratio compared to your friends?
different tires and/or tire pressure?

Could your t-stat be stuck, causing your truck to not warm up correctly
and thus burn more fuel? The dash gauges are not of much value.
An ODBII gauge will give you exact temps and immediately find a bad t-stat.
Engine coolant of 190* is a sign of a working t-stat.

Edit: By the way, I regularly get 17-18 and I got 21 MPG round-trip FL - NC (@70-75MPH).
I routinely go 700 miles on a tank (44 gallon tank in an Ex)
I filled up last week: 703 miles on 41.6 gallons (16.9mpg) no long hi-way trips on this tank.

 

Big Red Brute...

I also have 2005 F-250 CC Fx4. My mileage also sucks. I think it's just the way it is. These guys that claim 21 MPG are the following:

1. Lying
2. Don't know how to hand calculate
3. Are trusting their on-board computers
or...
4. Have tons of mods.

I am around multiple 6.0s from 2003 and up and from single cabs to crew cabs all 4x4s. They all get around the same mileage. Just the nature of the beast.

You shouldn't buy a truck for fuel mileage. If you want good fuel mileage, buy a Prius.

 

What are the rear end gear ratio's? That will explain something if different 3.73 vs. 4.04.

 

The biggest problem here is unrealistic expectations. The next biggest problem is having a liar for a friend.

 

Incorrect apostrophes cost 3.65 MPG at 65 MPH.

 

OK, here are some specs on my truck vs. my friends truck:

Mine: 2005 F-250 Harley Davidson edition. 6.0L, 5 spd automatic, Crew cab/short bed, 3.73 gears, factory 20's with factory sized Goodyear Wranger AT/S tires. 29 gallon tank. And I have a tonneau. No other accesories other than a bug defector and ventvisors. No power adders either. Milage after trip, 66421.

My friends truck: 2006 F-250 Lariat FX4. 6.0L 5spd auto, Crew cab/short bed, 3.73 gears, factory 20's with factory sized Goodyear Wrangler AT/S tires. 29 gallon tank. No bedcover, no bug deflector, no ventvisors, no power adders, and no other accesories. Milage, approx. 45000.

His truck does have exposed (factory) locking hubs, where as mine are hidden behind full hubcaps on the front. He has a lever operated transfer case whereas mine is the turn-dial, electric version. Other than that there isn't any difference. (Well except mine is blue and his is gold, but I don't think the blue paint has more drag than gold!) He and I discussed all this in our conversation earlier, and we both agreed that those minor differences in transfer cases/hubs shouldn't make that big a difference. And by the way, he's not a lier. I know his truck gets better milage than mine does, FOR A FACT BECAUSE I'VE DROVE HIS TRUCK!! And I hand calculated my milage after the trip as well and came within a couple of points difference of the on-board calculator.

I've known my friends truck since he bought it used 2 years ago. He replaced his 2003 F-250 extended cab with it. And his '03 got the same, if not slightly better fuel milage than is 2006.

The orginal owner of my truck used it to pull a fifth-wheel camper trailer on trips, and I wonder if maybe something about pulling such a trailer behind that truck might have messed up something in the transmission, or the electronic controls for the transmission. It seemed to me that the truck stayed a little higher than I would have thought in the RPM range going down the road. The tach read about 2000 where I would have thought it should have been somewhere around 1500 or so. But the truck seemed to shift fine throughout all the gears.