Idling your engine on cold mornings without driving it will do more harm than good.

Dear Car Talk

Dear Car Talk | Dec 01, 1993

Dear Tom and Ray:

I am an elderly woman, and I like to take very good care of my car. My question concerns a car that has to be left outside in the winter with no garage, and is only used about once a week. Is it wise when the temperature drops below zero to go out and start the car and let it idle for a few minutes?

TOM: Second to letting my brother borrow it, Lucie, that is just about the worst thing you can do to that poor little car.

RAY: First of all, you may do damage to the engine by starting it. When you start the car in that kind of weather, it takes a few minutes for the oil to really heat up and thin out. And until it thins out, it can't properly lubricate the moving parts of the engine. So those first few minutes are very hard on your car. So you should avoid cold starts unless you're really going to drive.

TOM: Plus, if you just start the car in weather like that, and just let it idle for a few minutes, the engine won't heat up. And the carbon and moisture produced by the engine never get cleared out, which is also bad.

RAY: So if you don't need the car, just let it sit there. It's not like a little puppy out there in the cold. It's just an inanimate object. Trust us. It doesn't care.

TOM: Oh no, now we're going to get nasty mail again from that old PHARTIO organization... People for the Humane and Respectful Treatment of Inanimate Objects.

RAY: If you do need the car in extremely cold weather, here are some of the tips we give in our pamphlet "Ten Ways You May Be Ruining Your Car Without Even Knowing It" (which you can get by sending $3 to .....). First, don't step on the gas pedal as soon as the car shows signs of life. Remember, the oil is very thick when it's cold, and revving the engine before the oil has thinned out will do a lot of harm. If it wants to stall, let it stall. That's better than revving it to death.

TOM: Second, if possible, plan your driving so that you drive the car for at least half an hour. Remember, the engine needs to heat up in order to get rid of that moisture and soot it produces. So try to avoid just using the car for really short trips.

RAY: Of course, when it's minus 6 degrees outside, that's when you're most tempted to use the car to go two blocks for a quart of milk. But do yourself a favor and consider calling a cab in those situations. Besides, the cab will already be nice and toasty the minute you get into it.

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