When my truck has been sitting in the cold for a while I usually let it warm up for a minute or so. You will notice that when first started, your truck idles higher than normal. I think it can be hard on the transmission to shift out of Park right away without letting the engine first idle down to the normal RPM. By the way, with all in-town driving, I am averaging about 10.5 to 11 MPG this winter. I don't ease into the throttle from stops either. I have 3.73 gears and 18" wheels.

 

it is important to get oil temps up. a 1 minute warm up is fine. water can condense in the oil in cold climates which can get in the cylinders and cause corrosion and poor combustion. well, the corrosion usually happens in the exhaust, not the engine. getting the oil temp up evaporates the water. not sure what this does to engine life.