I purchased the recommended viscosity in the Manuel. They do have the milage oil that is lighter in viscosity. Says it replaces 5-30.

 

I'm getting 7.1 on my 08. Not towing either.

 

I am still getting 14-15 driving @ 60mph. Im at 208k now.

 

Does the 2v do better then the 3v?
What year is your V10?

 

My V10 is a 2v. Its the V10 in my signature, 2000 F-250 SC/LB stock tire size.

 

They are close enough. The trucks with the 3Vs tend to be a little heavier, spin larger wheels and have bigger heavier rotors so that can hurt mpg on them some.

 

My mpg is really bad. The truck has no issues.

 

My current running average with my 08 dually 4x4 is
9.02mpg

Best: 11.3
Worst: 6.93

 

That's a dually. I have SRW

 

Understandable.

Dragging brakes?
Driving it like you stole it?
Do you have anything like a lift and big tires?

 

Big tires... I drive conservative

 

Bigger tires in town will kill ya, your pushing more rubber around in circles straining it in town from stop and go...

 

Ok, from what I understand (from reading on FTE) is that when you put on larger tires this will affect your trucks odometer. The larger tire is getting less revolutions per mile making it seem like you've traveled less miles compared to the stock tire size the truck is programmed for. So yea your mileage probably went down with the larger tire anyways but has been compounded by the effect the tires have on the odometer. I think there is a formula for recalculating mpg with the larger tire. Sorry I don't know what it is.

 

My recently traded '06 F350 FX4 CCSB - totally stock lost ~1.5 mpg on both local and open road driving, ~9.5/12.4 from 11 and 14 when E10 became the norm. This is with 4.10 gears. This truck, with the exception of too many sets of brakes, was totally bullet proof for 90,000 mile so I put up with the crappy gas mileage. Add a 12,000 pound 5th wheel, even one with an 'aero' nose, I would be happy with 7-7.5 on a long trip even with the engine 'screaming' at 4000+ rpm pulling a long hill. A 28 gallon gas tank with that trailer attached was never big enough - when you went down past 1/2 full, you were always looking for a gas station to easily get 34' plus truck in and reasonable easily out. As far as the LOM and hand calculation of mpg, they were always pretty close. I really like the 2011 6.7 diesel, 20.4 mpg open road empty/12.5-13 with the trailer and local driving, 15-17 but of course there are other costly things to maintain that a gasser doesn't have

 

I love my truck. It's bulletproof. Runs like a dream. So smooth. So much power. But 7.1mpg! !!!! Something's not right.