It’s something you may have been told for years: On a cold morning, start up your car or truck and let it idle for several minutes before you leave. Many people do this to warm up the engine and the cabin.
But car experts say that unless you are driving a much older car, you shouldn’t be doing that because it’s outdated thinking and it could end up doing damage to your engine.
Firestone says the advice about idling your car in the winter is from the carburetor age more than 40 years ago.
“In cold temps, carburetors couldn’t vaporize all the gasoline they let into the engine, so some of it would be left behind as a liquid rather than being burned off during combustion,” Firestone said on its website. “In order to work properly, a carburetor needed to warm up or else you’d run the risk of stalling out.”
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These days, that thinking is moot.
“Vehicles manufactured post-1980 have fuel management systems designed to heat up the engine fairly quickly,” says Jake Scheafer the Service Director at Smart Motors Toyota in Madison, Wisconsin — according to a blog post by the dealership. “Under normal wintertime circumstances, idling your car or truck for about 30 seconds is all it takes to get the engine above 40 degrees; ideal for typical operation.”
Firestone adds that your car will heat up faster when you drive it vs. just letting it sit.
There is, potentially, a major downside to idling for a long time when you first start the engine.
“Warming up your vehicle can actually shorten the life of your engine, by letting your vehicle idle in the cold you are actually stripping away oil from the engine’s pistons and cylinders each time you do this,” Smart Motors said.
“Constantly letting a cold engine idle can actually be counterproductive because it gradually strips oil away from the engine’s pistons and cylinders,” says a website post by Chuck’s Auto Repair in Seattle.
That can cost you money in repairs. But it can also cost you money at the pump because — you guessed it — you’re burning fuel while idling.
“A 2009 study in Energy Policy estimated that Americans waste $5.9 billion a year on gas while idling,” Firestone said.
So what about if you want to warm up the cabin in an electric vehicle? Experts say to take the opposite advice. Go ahead and warm it up, but be sure to keep it plugged in while you’re doing it.
“EVs have to draw on electricity to warm the interior. If you enter a car with a cold cabin and begin driving, the vehicle will need to take from its stored electricity to bring the inside air to a pleasant temperature. This will tax the EV’s battery and leave you with less driving range,” reads a post in the NAPA Auto Parts blog.
UPDATE: Since publishing this story, we have received some feedback from others questioning the advice above, saying there are other factors to consider. We wanted to highlight this one by a gentleman named Justin. Justin says he has worked as a factory certified dealership technician in Central Oregon and attended Central Oregon Community College majoring in automotive.
“The common misconception is that the quality/viscosity of current synthetic motor oils allows for more efficient lubrication within the engine. I implore you to take an engine oil of any weight and observe the drastic difference in the behavior of the oil when it is at 0 degrees as opposed to at 200 degrees,” Justin told us in a Facebook message. “My advice to the general public would to (at bare minimum) allow your engine to warm up at least enough to move the temperature gauge off of the cold mark. Ideally an engine should be at normal operating temperature before operating the vehicle.”
