Don't Warm Up Your Car ... Too Much

Jan 31, 2016 By Michael W. Pirrone

So, this is complicated. You’ve probably been hearing a lot these past few winters about what you should and shouldn’t do with your car. What to rub on your windshield to keep it from fogging. What you should fill a sock with to aid in that quest. Whether you should or shouldn’t warm up your car.

The Internet can really amplify the advice you receive from suggestion to command. When you see 40 people in your Facebook feed all sharing the same thing, maybe it’s time to listen. But fear, uncertainty and doubt might be fueling these continual reshares of advice, that while well-intentioned, might not exactly be sound.

The topic of warming up your car in the winter before heading out for the day has been the subject of some debate. There are self-proclaimed professional mechanics who swear on their mother’s grave you absolutely should. There’s a man with literally a doctorate in the subject of combustion engines, Stephan Ciatti, whose advice on the matter has been distilled via oversimplification down to “don’t ever warm up your car, ever, or you’ll break it.”

The truth, as always, lies somewhere in between. Let’s avoid any talk of severe cold. If you live in a place where you need an engine block heater installed, you probably already know what you need. But for the rest of us? If you have a modern car, we don’t recommend giving it more than five minutes of a warm-up. One or two is all that’s really necessary, and those “let me start my car and then have breakfast” marathon warm-up sessions? Those could actually damage your car!

When a modern engine is cold, the car knows to add more gasoline into the mix in the engine. This is great for getting it started. But if the engine doesn’t warm up quickly, that rich mix can lead “gasoline washing.” The gasoline can dissolve the oil seal on the cylinder head. Metal rubs against metal and leads to a bad time.

Once or twice probably isn’t going to kill your car. But those of you who rely on warm-ups to clear your windshield instead of an ice scraper? Take note.

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