I have a 00 F250 7.3 4x4 and I am looking to get better mileage out of it since it is now a dedicated work truck for towing. The two options I have in mind I think will work, but just wanted some clarification and if one is even possible.

First I will be taking the lift off and dropping back down to 33 inch tires or so. This should give me a little, but if not it should be easier on the truck for towing.

And this truck mostly see's highway miles, so I was thinking about disengaging the 4wd. I heard 4wd trucks get worse mileage, so this is the one I didn't even know if it was possible.

Any input on how and if would even work would be grateful. This is just the basics for now, and not digging in to the computer and injectors quite yet.

 

On a Ford, when your hubs are unlocked and the Tcase is in 2wd, your 4x4 is totally disengaged. You only are carrying more weight than a 2wd.
Tuners are the best way to increase mpg's once you go back down to closer to a stock height.
On my 7.3's, I opened up the exhaust and ran the open air filter known as the Napa 6637, neither of which are too expensive.

 

I also straight piped mine and did the 6637 filter. 33 inch tires are still too big in my opinion if you are wanting good mileage. Get a skinny tire without an agressive tread.

 

All of the above is great advice...how you drive is the largest contributing factor to MPG.

 

gas mileage, a large frontal area. high off the ground and weighting over 7,000 pounds.

very small improvements are possible.. very small

even removing the front drive and transfer case.. may give you 1/2 of 1... almost nothing.

stock size tires and wheels or Smaller, lower truck, lower air dam. maybe 2 miles per gallon. . my opinion... and go real soft on the throttle pedal ..


maybe consider a compact car.
.

 

Had a 1997 F Super Duty (450 before they called them a 450) with 7.3. Went with a DP Tuner 4 position chip and a K&N breather kit. I used the hardware but ditched the K&N filter and went with a Donaldson water resistant (marine) paper filter. Basically the same as NAPA 6637.
It woke the truck up some, because it was a slug. But better mileage was never realized. I think you're in basically the same boat. Like Chuck says, any gains will be minimal.
When I contacted 5 Star about improving the mileage on the F450 V10 in my signature, they told me to save my money. Because again, gains - if any would be minimal.

 

Taking the lift off will be a good start. Going back to the stock tire size will also be another place to go. Change all your gear lub to synthetic including differential engine transmission will also help. 2 MPG will equate to a 52 mile per tank increase. How many tanks a month do we use. over the year that adds up fast. If you have a bigger tank than it's even more.
Also correct tire pressure is a must. Stay away from tunes and CAI's. to go faster you need more fuel and air not economical at all. More fun but not what you want. Maintain the motor. Keep the air cleaner clean

 

The only way I was able to achieve better fuel mileage was through gearing. You must gear the truck appropriately for the load. I was towing 15k with 3.73s. That's a recipe for terrible MPG. I went to 4.56 and my mileage climbed 4 mpg. Also, in combination with this, slowing the hell down helps immensely. There's a sticker on your engine that has the fuel burn rate at a specific RPM listed. The closer you can get your final drive RPM to that with a corresponding lower load on the engine at that speed, you can effectively increase the MPG.