When temperatures are well below zero, get the engine started and let it warm up for perhaps two to five minutes, then shift into gear (assuming your vehicle has an automatic transmission). While holding the brake, let the engine idle for another minute or so in gear to begin warming the engine oil and transmission fluid under light load, then gently drive the vehicle up to temperature. This will warm up the vehicle as quickly as possible, bring the catalytic converter up to temperature to minimize emissions, and help the engine reach closed-loop operation with oxygen sensor feedback to maximize efficiency and mileage.

The reason is simple: this minimizes the time spent during the warmup phase. Everything is bad during warmup: the engine is running rich and producing higher emissions, deposits, and water vapor; piston blowby is at maximum, pumping the deposits and water vapor into your oil; engine wear is at the highest; oil circulation is poor causing higher wear, etc.

You want to get out of this phase as quickly as possible without harming the engine. The best way to do this is to start the car, let it idle long enough that it responds to throttle and can be driven smoothly, and then drive off. In extremely cold weather, you probably do want to let it idle for a minute or two, but as soon as the engine runs reasonably smoothly and responds to throttle normally, drive gently and accelerate the warmup process.

Leaving the engine idling for ten minutes while the car warms up and you finish your coffee is probably the worst thing you can do, but if you do want to do this, then I'd change oil more often to compensate.

 

Don't bother paying attention to wind chill temperatures when it comes to inanimate objects like vehicles. Wind only cools the vehicle off quicker. Once its temperature is down to the actual air temperature, the vehicle cannot and does not get any colder.

About warming up, today's new vehicles only need a minute or two for warmup. Anything more and you're wasting a lot of fuel. After that, put it in drive and go, but drive gently until it gets into normal operating temperature range.

 

I asked my dad about this. He's one of Cincinnati's best Porsche/Audi/Mercedes/BMW/Ferrari (name your expensive import) mechanics and has been for many moons (that's native American talk for 'a long time'). He's also involved in racing (was on pit crew for a Porsche team). http://www.germanmotorcars.com/ (and before anyone starts ragging on foreigns, neither my dad or myself owns a foreign car and I will be in heaven when I get my new F-150) Some of his clients (many I've met) have been Pete Rose, Jerry Springer, Anthony Munoz and others. So what I'm trying to say is, he's not some crackpot who likes to make things up for no good reason (and I'm not saying any of you are). I'm just saying I have an excellent reason to believe there is no problem at all with warming up a modern engine. Besides, even with a little oil contamination, it's no problem if you perform regular maint. on your vehicle. I've not seen an engine fall out of a car yet simply because someone decided to warm it up first...nor have I ever had any problems with my cars after having warmed them up many winters. I sold (not too long ago) a 3.1 Chevy Beretta with just over 225,000 miles on it and it still ran great. Anyway, this is what my dad said...

"With today's electronics it adjusts fuel and spark, cold or hot - i.e. emissions. On a carburetor engine if you let it idle cold it would dilute the oil and kill the lubrication. The rule for oil pressure is ten pounds per 1000 rpm. If your oil pressure is too low at idle it is too low at cruise rpm, you have a problem. Warming up your engine in extreme cold will lessen the chance stalling that can result from throttle body freeze up or a wide open position from freezing. There is also the safety aspect to consider. How many times have you seen people driving with frosted up windows? When you drive with a warmed up engine and the pre heater warming the throttle body, no freeze up will occur and your windows will be de-iced and stay that way even when you use the washers."

 

Now that it doesn't apply to me I just thought of something that noone has brought up. I remember many times firends and relatives not worming up their cars and getting down the road and the coolant thaws or some other thing finally works free and oops a broken car and your left in the cold. NOt that I ever warmed my car up, but the town I lived in was only 5 miles from one end to the other.