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Benefits Of Warming Up Your Car: How Long Is Too Long?

A car buried in snow. Ever wondered how long you should warm your car up? Here are the benefits to warming your car up for a few minutes, and reasons why you shouldn't let it idle for too long.

Physiologically speaking, the benefits of warming up your car are clear: When the temperatures drop into the single digits or into the negatives, driving isn’t comfortable. On the other hand, mechanically speaking, the benefits of warming up your car aren’t so clear. When it’s cold outside, should you warm up your car? If so, how long should you warm up your car?

The Obvious Reasons to Warm Up Your Car

Usually, the first thing we think of is to get the engine’s antifreeze flowing so you can get some heat in the cabin to warm frozen digits. If the windshield needs scraping, there’s no doubt a little heat makes the job easier. Still, aside from creature comforts, why should you warm up your car?

Warming up your car improves combustion, fuel economy and performance. The engine’s cooling system uses a thermostat to maintain its most efficient temperature range, usually around 200 degrees Fahrenheit. This operating temperature is about where the fuel vaporizes best. Many carbureted engines, usually pre-1995, won’t run very well if they aren’t warmed up.

Warming up the engine also improves lubrication and hydraulic efficiency. Engine oil and automatic transmission fluid (ATF) not only function as lubricants but also as hydraulic fluids. True, oil and ATF flow very well at even sub-zero temperatures, but every degree helps them flow better, improving lubrication and preventing wear.

The Not-So-Obvious Reasons NOT to Warm Up Your Car

Many places have implemented idling laws, not because they want you to freeze, but because the environmental risks are far more disastrous. Warming up your car is a waste of fuel, generating excessive emissions not getting you anywhere.

Warming up your car can increase engine wear. In both carbureted engines and electronic fuel injection (EFI) engines, usually post-1990, extra fuel is needed to account for poor fuel vaporization. In some cases, this could lead to cylinder wash-down or oil thinning, which could accelerate engine wear.

The Benefits of Warming Up Your Car for Just So Long

The benefits of warming up your car only go so far.What we really want is the best of all situations. We don’t want to be pumping out extra emissions for no reason — cold engines generate excessive hydrocarbons, carbon monoxide and nitrogen oxide emissions, which cold catalytic converters can’t process. At the same time, no one wants to freeze their glutes off in a frozen car, so just how long should you warm up your car?

Really, you shouldn’t need more than a few minutes to realize the benefits of warming up your car. For lubrication, hydraulic function and fuel vaporization, one or two minutes should be enough to get moving. Pushing warm-up time to five minutes doesn’t really add much warming, but it could make scraping your windshield easier. To get yourself warmed up, dress for the weather and remember scraping is good exercise.

Still, more of a good thing isn’t better, so don’t warm up your car for 20 minutes. To get your engine to operating temperature faster, for best fuel economy, emissions, performance and cabin heat, you have to get out on the road, but take it easy for the first five to 10 minutes. In sub-zero weather, using a block heater a couple of hours before you start your engine gives warming a head start.

Check out all the heating & cooling systems parts available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on how long you should warm up your car, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Flickr.


Benjamin Jerew View All

Ben has been taking things apart since he was 5, and putting them back together again since he was 8. After dabbling in DIY repairs at home and on the farm, he found his calling in the CGCC Automobile Repair program. After he held his ASE CMAT for 10 years, Ben decided he needed a change. Now, he writes on automotive topics across the web and around the world, including new automotive technology, transportation legislation, emissions, fuel economy and auto repair.

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