Should You Warm Up Your Car Before Driving?

CR’s expert explains why letting your car idle might not be the hottest idea 

Women looking out window at car covered in snow Photo: iStock

It’s easy to understand the appeal of getting into a warm car when the temperatures outside begin to drop. Some drivers are also convinced that letting the car warm up before driving is also better for the engine. But is warming up your engine before driving really a good idea?

Consumer Reports Chief Mechanic John Ibbotson says that giving the engine a chance to run for a minute before driving on a cold day is smart but that there isn’t a need to let it run longer beyond warming the cabin and defogging the windshield. And there is a real downside: consuming fuel and generating emissions.

An engine is fully lubricated long before it reaches full operating temperature. When your car sits for an extended period of time, the oil drains down to the bottom of the oil pan. Once you start the engine the oil pump quickly circulates the oil throughout the motor, lubricating all the necessary moving engine components. A cold engine idles at 1,200 rpm or more, making quick work of the lubrication process. Being mindful to give your engine a chance to lubricate, along with being diligent about routine maintenance, can help most modern engines last 200,000 miles or more. 

There was a saying with older engines that the worst thing you could do for a motor was start it because for a split second those engines were somewhat dry and weren’t well lubricated with oil.

Modern cars have improved on technology to the point that your engine is fully lubricated within 20 to 30 seconds. By the time you get in, start the car, put on your seatbelt, and get situated, the engine might not be fully warm, but it’s completely lubricated and you’re okay to drive at this point.

When temperatures drop during winter it’s a good idea to let the car run for about a minute. Some drivers prefer to let the engine idle for 20 minutes or longer to get everything—including the cabin—really warm, but the fastest way to warm up an engine is by driving. Just remember to not rev the engine hard for the first few minutes of driving until you see the temperature gauge move off the cold reading.

In terms of comfort, when you drive the car it’s going to warm up in just a few minutes vs. idling for 15 or 20 minutes. Extended idling just wastes gas.