8mpg!!!
make sure they are freewheeling. i had a brand new from the dealer caliper lock up on me 2 months ago.
my 02 needs the tube cleaned and has dropped from 15 mph to around 10 mpg.
another thought. are you using the lie o meter for mileage, or hand calculating? because the lie o meter will be wrong with a chip or tuner.
and get rid of that edge and put a chip with custom tunes in the truck, you will be much happier with the way it runs.
Ford Trucks for Ford Truck Enthusiasts
1999-2004 Ford Super Duty Winter Grille & Bug Screen
FIA Part #WA922-7
FIA Custom Fit Winter Front Bug Screen for 1999 2004 Ford F 250 F 350 F 450 New | eBay
Also available from AutoAnything:
Fia Grille Covers, Go Fia Winter Grill Cover, Truck Grille Covers
Given your chronic PMS, and your location, I'm surprised you don't already have one!

In any case, 190 deg is too cold for optimal combustion in these motors. Even little 4cyl gas motors run hotter then that, for efficiency (generally 205-210 deg operating temps).
At 190, you aren't even opening the stock Ford t-stat, let alone the hotter IH one many people switch to. Its not good to drive around with a "permanently" closed t-stat. With restricted coolant flow, you will have various "hot spots" in the motor that aren't getting proper cooling.
I've had mine on for a few weeks. Temperatures have ranged from in the teens, up to mid 40's for a few days. During that time, I've done high speed highway driving, in town "normal", and in-town "crawling in traffic for an hour +". I've done this empty, as well as with 4,000LBS in the bed. I've run in stock, daily driver, and the tow tune. I've gone easy on it, and I've driven it like I stole it. The dash temp gauge has never climbed higher then half way, which is where it pretty much stays at no matter what, only slightly cooling off with either extended idle or extended highway running.
I actually made my own last year, out of cardboard covered in clear packing tape. It looked pretty ghetto, but it worked. It only started to fall apart as spring started, since it was then exposed to a lot more liquid water, instead of just snow/ice/slush that quickly refroze. Again, I had no overheat issues last year either. Even with the cover on, tons of air still gets through, via the gap between the grill and bumper, as well as the opening in the bumper.
As I also mentioned, grill blocks can offer aerodynamic improvements, by reducing drag, and even improving handling at highway speeds.
The inside of your engine compartment is basically a big square parachute. Air gets shoved in faster then it can get back out, and creates a positive pressure. First, this causes drag, reducing fuel economy. Second, that trapped air/pressure pushes up on the hood, and anywhere else it can, and causes a small amount of lift. While you aren't going to need to contact the tower for takeoff clearance, it can be enough lift to cause the front tires/steering to feel "light" and "darty". Turbulence from heavy wind gusts and/or passing tractor trailers can amplify the effect.
By blocking the grill off, you can substantially reduce the amount of air getting packed into the engine compartment. Anything you do in this area will help. If you can block enough of the air, without causing the vehicle to overheat, you might even be able to create an area of negative pressure under the hood, resulting in "down force". This will make the front end feel more "planted", and improve highway stability. Granted, too much down force can increase drag and reduce fuel economy, but I doubt you would be able to (or want to) seal the Super Duty engine compartment enough to worry about that.
Also, several of the major auto manufacturers (Ford, Dodge, various GM divisions) are now including adjustable, computer controlled grill block offs, commonly called grill "shutters" on several car and truck models.
Active Shutter Grille Vents: How They Help Improve MPG
Active Grille Shutters Are Latest Way To Improve Fuel Efficiency | Edmunds.com
and after 5 minutes i have to open the window because it is too damn hot in the cab.
same with my 88 diesel.
the crown vic on the other hand takes 10 minutes of driving to get any heat.
Wow, at that temp I peak out at about 165 degrees unless I put a large load on the truck - for example back to back WOT tests.








