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Unfortunately some of us have to drive large trucks either because of climate, work, location, or any combination of other things. Most of these large vehicles get very poor mileage, but but with proper care and maintenance we can improve it slightly.
Step 1Get a topper or cover for your truck
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Mythbusters have proved that these aren't the most fuel efficient when the truck is empty, but they didn't try it when it was full of wood or old appliances. A topper can really help when you are hauling bulky unaerodynamic objects by reducing the drag from wind.
1:
http://www.cumminsforum.com/forum/2010-general-discussion/346926-why-do-diesels-need-grille-cover-when-cold-we-have-thermostats.html
2:
http://www.astrosafari.com/viewtopic.php?f=9&t=5321&view=print
3:
http://www.thedieselstop.com/forums/f31/cold-weather-grill-radiator-cover-75746/
*Also, note that it actually would decrease how aerodynamic the truck is due to the restricted airflow. You are forcing more air around the cab, rather than allowing some to pass into the engine, and flowing out through the bottom or other parts. And while I may not be a trucker, I am an engineer with experience studying aerodynamics in a wind tunnel. A truck, depending upon the design, is one of the worst aerodynamic shapes out there, with the best being a theoretical "perfect" teardrop shape. Basically, a truck is a big rectangular prism, and rectangular prisms are in fact the worst aerodynamic shape when you look at simple shapes. You could design something to be worse, but there's no need for that.
http://www.peterbilt.com/eco/pdf/Aero%20WHITE%20PAPER-2.pdf
The pictorial representation may help you. I would draw your attention to the grill area on both trucks. Notice how there is in face a color other than red there, meaning air is allowed to pass through and escape with less of an impact upon the aerodynamics of the design. Now visualize placing the bra over the grill. You do not dispute it restricts air flow correct? Now notice the wind shield, see how, due to it being solid, it is almost exclusively red? That is comparable to the result you would have when covering the grill. This clearly shows that solid surfaces are worse than those that are slotted to allow airflow. As the bra is made to restrict the airflow further, more of the actual air drag will be placed onto the truck, resulting in lower aerodynamics. And this hasn't become a question of performance. For that I would have you look at the older caterpillar engines. Quite a strong engine. Though a truck is suited to only a few tasks, same as cars. They out perform each other in different areas.
*Note: It may not be "text talk" but it "appears" to show that you can't be bothered with speaking correctly, something that employers, especially in engineering fields, take notice of. I would never have received any of my jobs had I spoken similarly. No offense to you, I just dislike how many people speak that way in general, and tend to react negatively. I have poor social skills when dealing with something like that, certain things just rub me the wrong way and I can't stop myself from saying anything. One of the pitfalls of us engineers is that we tend to have worse than average social skills, and many quirks. So apologies if that seemed like a personal attack. May we start over? If I haven't already burned any bridges...
(Besides, driving 4WD when you don't need to is really hard on the car.)
ONLY USE APPROVED COOLANT!!!!!!!!!!!!!
approved coolant will be red
from the manual:"Using unapproved coolant may damage engine."
GM's Dex-Cool coolant shouldn't be mixed with other generic coolants, though, there's the possibility that the two can react and form a gel within the cooling system. Nasty stuff.