Originally Posted by nobagger
Our 06 250 SD has a 5.4L with a K&N air induction kit and a super chip and it seems to get 10-12 no matter what its doing, even empty. Our enclosed trailer is 24ft long and always loaded with equipment totaling (with trailer) about 8k. Our 05 F350 SRW has a 6.0L PowerStroke and we just got it so I can only guess from what Ive read and heard expect to get mid teens. I think for around town towing and occasional hi way towing your better off with a V-10, Ford's V-10's put out almost 500lbs of torque!
Screw the V10. I know with my load the mileage would go down at least 3 or 4mpg. Quite a few ppl I know are pulling similar loads with big gas motors and I couldnt take getting 6-8mpg.