15.8-16 around town, 18 or so highway, (not towing).

Eisboch

Well first of all, My truck is a F-450 4x4 crew cab, 6 speed, DRW 4.30
gears.  This truck has a 9.5 foot long 8 foot wide flatbed with two 18x18x36
side boxes and weighs in at 10,300 pounds full of fuel (59 gallons) and
empty of cargo.  The 2005 F-350 SRW configured the same, 6.0-liter, Loaded
Lariat etc. weighs in some where around ~7000 pounds.

I have over 15,000 miles on my '05 6.0-liter Power Stroke diesel, 10,000 of
that towing.  Not a hiccup, not a single drop of anything leaking from
anywhere.  Zero oil consumption.   The entire truck has been totally trouble
free.

Driving easy without a trailer, mixed around town short highway trips, I am
getting between 13.8 and 14.7 MPG each fill up.  If I stomp on it all the
time it gets 12.5-13.5 MPG.  Not as big a difference as I expected between
driving easy and not.

Pulling one of 4 different trailers, 5th wheel RV ~9000 pounds, 4 Horse
Goose Neck ~7500-15,000 pounds depending on load, 18 foot long extra tall
covered Wells Cargo trailer ~4500-10,000 pounds depending on load and a tilt
bed flatbed trailer ~4500-10,000 pounds.  If I keep it under 60 miles per
hour, I'm seeing 11.5-12.5 MPG no mater how I drive and traveling 65-85 MPH
I get 10.5-11.5 MPG each fill up.  All of this mileage is with windows up
and the automatic temp controller on in the warm weather so the air
compressor is engaged.

The pulling power is OUTSTANDING. I just pulled a Corvette (3218 pounds) on
a tilt bed flatbed trailer (4500 pounds) just under 8000 pounds from
Sacramento California to Detroit Michigan east on Interstate 80, and for the
most part left it in overdrive on cruse control.  When I stomped on it up
the hills most rigs had trouble not being left behind.  :-)

The best information I can gather, talking about the 2005's is all else
being equal, the diesels will see 25%-50% better fuel mileage than the same
truck with a gas engine.  If you drive above sea level, or do a lot of
hill/pass driving, you will notice that the turbo charged diesel does not
suffer from that dreaded -10% power loss per 1000 feet of elevation gain
that the naturally aspirated gas engines do (thinner air).

I actually seriously considered the 6.8 liter 30 valve 362 Horsepower 457
Torque gas engine when I ordered this truck, I am SO GLAD I decided to go
with the 6.0 liter 32 valve 325 Horsepower 570 Torque diesel engine.

Outstanding!  :-)

That is about as good as it is going to get.
A few other things that will help are:
keeping your tires inflated, I run mine near the max pressure most of the
time.
Make sure your air filter is clean, when it starts to restrict your air
intake it will decrease your fuel mileage.

But it is damn hard to keep from stomping on that monster isn't it?  :-)

I have to keep my trucks computer set on the MPG selection so it can keep
reminding me not to stomp on it.
I have found that if I keep the factory boost gauge under 10 pounds of
boost, I get my best fuel mileage.
10 pounds or less of boost makes for pretty easy starts.  :-)

Enjoy your truck.

Yeah, that's what I've managed with my V-10 in the past.  Don't see it
now, but used to see 13-14 all the time with a one hour, 40-50 mph
commute I used to have.  What really amazed me was when my truck
averaged 14.5 mpg comming across the (flat) central US while loaded
down and towing a loaded 2-place snowmobile trailer.  The reason?  My
wife was driving it following me in an overloaded Ryder rental truck
that wouldn't do over 60 mph.

Matt
99 V-10 Super Duty, Super Cab 4x4

I also have 4.30 gear 5 spd manual and put 285's on as well but that brings
the gear ratio to about 4.10 or so, so how does that give you worse mileage?
Not being a jerk I just thought that 4.10 would get better mileage than a
4.30. I never understood the bigger tires worse mileage, smaller gear better
mileage. please explain. By the way i just saw in the jcwitney catalog a
throttle body spacer for 90 bucs this should help on mileage a smidge.

Chris 00 250 SD CC 4.30 5SPD 4X4