Do you need to warm up your car in winter before driving? I spoke to over 30 mechanics and didn’t get a clear answer.

When warming up your car in winter, experts said you should consider the environment and engine maintenance.Henrik A. Jonsson/Shutterstock

  • Automakers don’t have consistent advice on how long you should leave your car out in the cold.

  • So it’s no wonder mechanics don’t all agree on the subject either.

  • In general, it may help to keep the car running smoothly if it idles for about 30 seconds when it is cold.

It’s cold outside and you’re late. Is it OK to just start your car and go, or should you wait for the engine to warm up a bit before hitting the road?

I’ve found myself in this predicament many times this winter, wondering if my impatience – and bad time management – is taking its toll on my car or the environment.

So I did what anyone could do: I called my mechanic. Then I called a second mechanic for good measure. To my surprise, they had completely different advice.

One told me to let the car idle for three to five minutes before driving, while the other told me not to wait at all. I called a third engineer to solve the matter, but he only told me something completely different, which was to wait 30-60 seconds.

At that moment I had a mission. I called half a dozen mechanics in half a dozen states for some semblance of clarity. I got recommendations that ranged from 0 seconds to 10 minutes.

Why all the confusion?

cars covered with snow in front of a house after winter storm

A massive blizzard hit Toronto, Ontario, Canada, on Jan. 25, 2023. The storm is expected to drop between 8 and 10 inches of total snowfall in the Greater Toronto Area and officials are calling it the most significant winter storm of the season so far.Creative Touch Imaging Ltd./NurPhoto via Getty Images

No wonder there is confusion. But first let me say it’s not because of the common myth: that cars prior to the 1980s ran on carburetors, which had to be warmed up in the cold for several minutes or else they would stall, which is why modern engines need the same (they don’t ).

They’re real carburetor engines and the cold can’t get along, but that’s not why the 30-plus mechanics I spoke with couldn’t agree on how long to warm up my 2013 Honda Civic. They clearly knew that my Honda has no carburetor.

The confusion falls somewhat on automakers.

In a report from the Oak Ridge National Laboratory, researchers gathered idling recommendations from owner’s manuals of several brands, including Ford, Chevrolet, Honda, BMW, Lincoln and many more.

Some manufacturers had no advice on idling – my Honda owner’s manual falls into this category. Others, such as Ford and Chevrolet, recommended idling no more than 30 seconds after starting.

While Infinity and Nissan advised idling at least 30 seconds. And Toyota suggested idling for “a few tens of seconds” – whatever that means.

So how long you should let your car idle in the cold seems to depend on the make of your vehicle. But if you’re like me and your owner’s manual doesn’t contain any advice, here’s a good rule of thumb.

A good rule of thumb that takes the environment into account: about 30 seconds

Despite the debate whether the optimal idle time is more, less or around 30 seconds, that 30 seconds seems like a good rule of thumb for most drivers on cold days.

This is because the engine oil in your car drains to the bottom of the engine after the car has been sitting for more than a few hours. When you start the ignition, the oil moves through the engine and lubricates the pistons, cylinders and other moving parts. On a hot, sunny day, that process happens almost instantly, but when it’s cold outside, the oil moves a little slower and therefore takes a little longer.

How much time mechanics differ on the subject, but about 30 seconds is the general consensus for modern engines. On extremely cold days you may need about a minute, but no more. Why some mechanics told me this process takes five to ten minutes I don’t know.

What I can say is that if you’re idle for much longer than 30-60 seconds, you’re just wasting gas and money. For every two minutes you idle, you lose a mile of gas mileage, which, depending on the car type and fuel prices, can cost tens to hundreds of dollars a year in wasted gasoline.

Idling also doesn’t charge the car’s battery properly and can shorten battery life. Plus, it contaminates your engine oil, according to the Oak Ridge report, leading to more oil changes than you would otherwise need.

And last but not least, you unnecessarily pollute the environment.

“You have more emissions when the engine is idling than when it’s running,” which is worse for the environment and why more than half of U.S. states have laws against idling, said Bassem Ramadan, department head and professor of mechanical engineering at Kettering University. .

What mechanics agree on: Don’t floor it right away

A car.

A car.Getty Images

Whether they tell you to idle for 10 seconds or 10 minutes, every mechanic agrees that you shouldn’t slam on the gas when you first start riding in the cold.

The cold causes metal in your engine to contract, creating tiny gaps between moving parts that can put stress on it, said Phil Carpenter, director of operations at Urban Autocare and Avalon Motorsports in Colorado.

“Everything in an engine has tight tolerances,” Carpenter said. After the car warms up, “all the metal expands and things start to fit the way they should.”

Shooting your engine already strains it, even if everything is running smoothly. If you shoot it and those holes are there, it’s a lot worse, Carpenter said. “That’s when your turbo can fail in that 60 to 90 thousand mile range. It’s not a guarantee…but the odds are higher.”

According to Ramadan, depending on weather conditions, it can take about five minutes after you start driving to get a car up to temperature. If you let the car idle instead, it will take longer.

This is also why, even for people who advocate long downtimes to heat their cabs for comfort and defrost their windshields, it’s clearly better to drive than to idle, because your car heats up much faster when it’s running.

Yes, you will be cold for the first few minutes and you may have to take a slow drive around the block a few times before hitting the main road to give your defroster time to warm up.

But in the end you save some money and help the environment.

Read the original article on Business Insider

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