For years traditional wisdom has told us all that it is necessary to idle your car for at least 5 minutes to warm up before driving during the cold, winter months. Perhaps your mother or father told you how long to warm up the car in winter, and they passed the practice down to you. However, for modern cars, this requirement is nothing more than an unnecessary myth.
How Did the Myth Start?
Like many myths, the origin of the practice is rooted in truth. At one point, it was necessary to warm up cars before driving them in cold weather.
Before the 1980s, cars used carburetors to mix air and gasoline to run the engine with vaporized fuel. When the gasoline was too cold, and wouldn’t effectively evaporate, cars would stall out. Idling your car allowed the carburetor and gasoline to warm up enough to run smoothly.
Modern cars now use electronic fuel injection instead of carburetors. As mentioned before, when the air is cold, gas does not evaporate as easily. Modern cars use sensors to detect when the temperature is cold enough that the air-fuel mix needs to be adjusted. Your car will automatically add more gasoline to the air-fuel combination, which allows it to combust and evaporate more easily. Once your car warms up enough, the air-fuel mix will adjust back to normal levels.
The switch from carburetors to electronic fuel injection happened throughout the 80s and early 90s, so unless you’re driving a car that predates the change, you no longer need to warm up your car for 5 plus minutes when it’s chilly.
What About the Oil?
Some people argue that they idle their car for the sake of warming up the oil, not the engine. A better way to combat this is to use oil that is recommended by your car manufacturer for cold weather driving. Your automobile’s manual should have that information.
Are There Negative Consequences for Idling in the Cold?
First, idling causes needless emissions and pollution. It can also impact your fuel mileage. While most cars get worse gas mileage when the car is cold, it is never worse than idling, which is a whopping 0 miles per gallon. Your fuel efficiency will improve as your engine heats up while driving.
Idling your car in the cold for long periods of time can actually shorten the life of your engine rather than extend it as many believe. Because your car puts more gasoline into the air-fuel mix, more gasoline makes it into the combustion chamber in order. This makes it easy for the fuel to wash the oil off the cylinder walls if your car idles for a long period of time. This, in turn, can also affect the lubrication of cylinder liners and piston rings, which can lead to a shorter life of those parts.
What Should You Do to Warm Up the Car?
If it’s really, really cold outside, warm up your car for about 30 seconds (though some cities and countries recommend longer idling for extremely cold weather below 0° Fahrenheit), and gently start driving. To put it simply, the fastest way to warm up your engine is to drive.
It’s important to keep two safety warnings in mind:
- Drive gently while your car is warming up. If you floor it as you first start driving, you will put unnecessary stress on your engine and waste gas.
- Always clear your windows and mirrors to provide proper visibility when driving.
Stay safe and warm all winter long! For more information on how to winterize your car, read our other blog posts.