Gentlemen:
I am a "Newbie" here looking for some info. I have been driving nearly 51 years and have never seen or experienced anything like this. I ran across a brand new 2010 F250 5.4L 6 speed manual still sitting on the lot in summer of 2011. I have always been a manual transmission fan, was not really needing a new truck, but knowing they were no longer available; I made them a stupidly low offer which they refused. They called back a couple of months later and accepted. It has so far been a great truck; except for one thing. In the hot summer months I get about 19.5-20.0 MPG going back and forth to work, mostly (about 2/3) highway around 60MPH average. In the winter this drops about 2.5MPG to 17.0-17.5MPG. When it very occasionally dips into the mid-low 20's here, it will drop 3.0MPG or more. I have owned Ford and Chevy/GMC trucks, and many different cars, and driven many other vehicles over the years, and never seen this before. A small maybe 5-7% drop in winter; but not this. Truck seems to run fine, no engine lights, had a dealer hook it up and check, and he said all was well. I just can not believe this is normal for this engine and truck. Do any of you have this same problem, or heard of this. Better yet, do you have a fix?


Thanks in advance-
La_Swampfox