CHICAGO (WGN) — As below-freezing temperatures continue to impact several areas across the U.S., a common practice for drivers when it comes to heating cold vehicles may prove obsolete.

For many, it’s a question that was thought to have an obvious answer: Should you let your car warm up before driving? Does allowing the engine to run for a few minutes before driving help with performance?

While it’s certainly nice to enter a warm car rather than a cold one, especially in the harsh winter months, this age-old advice about automobiles is more myth than fact, according to the American Automobile Association (AAA).

AAA says drivers should “start the engine and allow it to idle only for the time it takes you to fasten your seat belt.” The reasoning, AAA says, has to do with the way oil cycles through the engine.

“Driving the car normally and avoiding hard acceleration brings the engine to a warmer temperature faster, and also reduces wear and exhaust emissions,” AAA wrote.

AAA says, however, that idling the car for “a little longer” is still acceptable, especially when cleaning snow from the vehicle.

Brutally cold temperatures and dangerous wind chills stayed put across much of the U.S. on Monday, promising the coldest temperatures ever for Iowa’s presidential caucus, and testing the mettle of NFL fans in Buffalo for a playoff game that was delayed a day by wind-whipped snow.

About 150 million Americans were under a windchill warning or advisory for dangerous cold and wind, said Zack Taylor, a meteorologist with the National Weather Service in College Park, Maryland, as an Arctic air mass spilled south and eastward across the U.S.

The Associated Press contributed to this report.