Automakers don’t have consistent advice on how long you should idle your car in cold weather.
It is therefore not surprising that the mechanics do not all agree on the subject either.
Generally speaking, idling your car for about 30 seconds when it’s cold can help it run smoothly.
It’s cold outside and you’re late. Is it okay to just start your car and drive away, or do you have to wait for the engine to warm up a bit before hitting the road?
This winter, I have found myself in this predicament many times, and it has made me wonder if my impatience – and poor time management – is having an impact on my car or on the environment.
So I did what anyone could have done: I called my mechanic. Then for good measure, I called in a second mechanic. To my surprise, they had completely different advice.
One said to idle the car for three to five minutes before driving while the other said I didn’t need to wait at all. I called a third mechanic to fix the problem, but he just told me something completely different, which was to wait 30-60 seconds.
At that time, I was on a mission. I called half a dozen mechanics in half a dozen states for some semblance of clarity. I received recommendations ranging from 0 seconds to 10 seconds minutes.
Why all this confusion?
No wonder there is confusion. But, let me first say that it’s not because of the common myth: that pre-1980s cars ran on carburetors, which had to be warmed up for several minutes in the cold or they would stall, and so modern engines need the same (they don’t).
It’s true that carbureted engines and cold don’t get along, but that’s not why the 30+ mechanics I spoke with couldn’t agree on how long my Honda Civic should warm up. 2013. They obviously knew my Honda didn’t have a carburetor.
The confusion falls somewhat on the automakers.
In a report from the Oak Ridge National Laboratory, researchers compiled idling recommendations from owner’s manuals for various brands, including Ford, Chevrolet, Honda, BMW, Lincoln and many others.
Some manufacturers lacked guidance on idle time – my Honda owner’s manual falls into this category. Others, such as Ford and Chevrolet, recommended idling for no more … than 30 seconds after startup.
While Infinity and Nissan advised idling for at least 30 seconds. And Toyota suggested idling for “a few tens of seconds” – whatever that means.
So, how long you should idle your car in the cold seems to depend on the brand of your vehicle. But if you’re like me and your owner’s manual lacks guidance, here’s a good rule of thumb.
A good rule that takes into account the environment: about 30 seconds
Despite the debate over whether the optimal idle time is higher, lower, or around 30 seconds, 30 seconds seems like a good rule of thumb for most cold-weather drivers.
This is because your car’s engine oil is draining to the bottom of the engine after the car has stood still for more than several hours. When you turn on the ignition, oil moves through the engine to lubricate the pistons, cylinders and other moving parts. On a hot, sunny day this process happens almost instantly, but on a cold day the oil moves slightly slower and therefore needs a little longer.
How long mechanics differ on the subject, but around 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 10 minutes, I don’t know.
What I can say is if you idle for more than 30-60 seconds you are just wasting gas and money. For every two minutes you spend idling, you lose a mile in gas mileage, which, depending on the type of car and fuel price, can cost tens to hundreds of dollars a year in wasted gasoline.
Idling does not properly charge the car battery and can shorten battery life. Plus, it contaminates your engine oil, the Oak Ridge report pointed out, leading to more oil changes than you would otherwise need.
And finally, you unnecessarily pollute the environment.
“You have more emissions when the engine is idling rather than when it’s driving,” which is worse for the environment and why more than half of US states have anti-idling laws, Bassem said. Ramadan, Head of Department and Professor of Mechanical Engineering at Kettering University.
What Mechanics Agree: Don’t Put It Down Just Yet
Whether they tell you to idle for 10 seconds or 10 minutes, all mechanics agree that you shouldn’t press the throttle when you start driving in the cold.
The cold causes the metal in your engine to contract, leaving tiny gaps between moving parts that can fatigue it, said Phil Carpenter, operations manager at Urban Autocare and Avalon Motorsports in Colorado.
“Everything in an engine has tight tolerances,” Carpenter said. Once the car warms up, “all the metal expands and things start to fit the way they’re supposed to fit.”
Gunning your engine already tires it out even when everything is running smoothly. When you pull it and those gaps are there, it’s much worse, Carpenter said. “That’s when your turbo can fail in that 60-90,000 mile range. It’s not a guarantee…but the likelihood is higher.”
According to Ramadan, depending on weather conditions, it can take about five minutes after you start driving to bring a car up to temperature. If you slow the car down instead, it will take longer.
It’s also why, even for people who advocate long idle times to warm up their cabins for comfort and defrost their windshields, it’s unequivocally better to be idling than idling because your car will warm up much faster when ‘she rolls.
Yes, you will be cold for the first few minutes and you may have to drive slowly around the block a few times before turning onto a major road to give your defroster time to warm up.
But in the end, you’ll save money and help the environment.
Read the original article on Business Insider