ill put this here again, just for completeness no more than a minute of time is needed at initial startup to warm modern engines


why is it bad to let your truck warm up (warming up is actually left over from the days of carburettors which would not atomize the fuel properly when they were cold, this required warming up the engine, modern electronically fuel injected cars do not face this issue)

1) waste gas (at idle your truck gets 0 miles per gallon of fuel burned, the reduction in mpgs while you are warming it up but driving is still better than 0)
2) engines run rich when they are cold (this is the computers attempt to warm them up faster, it works, but also emits alot more pollution)
3) the catalytic converter works best when it is warm, it warms up from exhaust gases, running at idle (ok, just above idle when its cold) gives off relatively LOW exhaust gas temperatures hence warming up the CAT more slowly, making it work harder and less efficiently, and less effectively.
4) this can cause the cat to become plugged over time (not right away of course, but over time if you do this alot it will happen)
5) engines warm up faster when being driven GENTLY (dont go and stomp on the gas immediately, wait for the water temp to come up)
6) rich burn leaves more deposits in the engine (carbon build up ect) this fouls plugs and causes a general loss of efficiency in the engine over time.
7) rich burn leaves fuel behind to mix with the oil in the crankcase, diluting the oil and making it less effective


now you do need to wait long enough for your oil pressure to come up however that is maybe equivalent to the time it takes to put on your seat-belt, and at that point you should be good to go.(maybe a minute at most)



sources :

http://www.abc.net.au/science/articl...27/2044311.htm
http://www.popularmechanics.com/cars/how-to/4213313

 

We've been lucky with very few 0 degree days but it is guaranteed the in jan and feb there is a few weeks were 0 is a heat wave. Highs -8 degrees and lows -35 degrees, so mine will high idle like 1100rpm and I will drive when it reaches 700rpm. I usually don't have to let it run at all in the morning cause its in a heated shop. Call me old school if you will.......
Diesels on the other hand should be idled.

 

diesels seem to be much more friendly to idling than gasoline engines, and im really not 100% sure on why this is, probably has something to do with the compression ignition system on them.

 

Yeah, they warm up the fastest with less wear and need to warm the turbo before heavy use. That and the heavy oil they use needs to warm up so the oil pressure doesn't go through the roof. They also don't use much fuel at idle.

Wow did this get off topic in a hurry.......

 

the guys problem was solved so its not a big deal, and there is good information in the off topic posts too