What Is Idling and Does It Help Your Car? The Myth of "Warming Up"

By John Stahel - April 18th 2017

idling engine
Image Courtesy of Pixabay

Many drivers believe that turning your car on and letting it idle before driving can protect your engine, however, experts say this myth might actually be hurting rather than helping. Motorists, especially in the cold winter months, are known to go out and turn their cars on anywhere from 2 to 20 minutes before they get in and drive off.

Although this is quite an effective way to warm your car, many drivers also believe idling gives the engine needed time to warm up and protects it from possible damage. The truth of the matter is that not only does letting your engine idle waste fuel, but it actually strips away oil from the cylinders and pistons.

Now for a little bit of technical background.

Combustion engines generate propulsion by igniting a combination of air and vaporized fuel in each of the engine’s cylinders. In the cold, vaporization becomes more difficult so modern engine controllers pump excess fuel into the cylinders to create the right proportions for combustion. According to experts, this influx of gas can actually wash oil off of the cylinder walls causing unnecessary damage to your vehicle. Without the oil as lubrication, the life cycle of these vital engine components can be greatly reduced.

The exaggerated release of fuel also wastes unnecessary gas. When the engine hits a suitable operating temperature of 40 degrees Fahrenheit, the fuel can vaporize normally halting the excess use of gas in the combustion process. Unfortunately, idling does not effectively heat up the engine so the only benefit of letting your car idle is being able to step into a nice, toasty car in the morning.

Then what can you do to make sure your engine is running safely and efficiently? Simple, just drive.

Using your engine for what it was made for proves to be the most effective way to warm up your engine and prevent the use of excess fuel and the stripping of oil from the cylinders and pistons. Engines can take anywhere from 5 to 15 minutes to warm up, so make sure to ease into your trip rather than gun it and put unnecessary stress on your engine.

Where did the "warming up your car" myth even come from?

The warming-up-your-car myth originated decades ago when most cars on the road were carbureted and lacked sensors that controlled the mixture of gas and air in the engine. Since current cars use sensors to monitor fuel injection, warming up your vehicle has become an obsolete practice. We hope our debunking of this myth has taken the mystery out of auto car for you.

RepairPal is working to mend the lack of trust consumers have in the car repair industry by providing them with in-depth knowledge and resources that connect them with dependable and reliable car repair shops near them.

Our goal is to establish an auto repair process that is less stressful and much more trustworthy for everyone involved. Our website hosts a car repair Estimator that gets rid of that "ripped-off" feeling. We also provide matches to local Certified shops that are guaranteed to do repairs with quality parts, a fair price, and a trained, awesome staff.

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2 User Comments

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wow, ive been idling w/ my car for years to warm up the engine, thanks for the good tips!
So how do you deal with the other things that happen during cold start, like thermal expansion and the low viscosity of oil that may be unable to seep well and evenly into piston pins and main bearings. And who are these "experts" that you forgot to mention, who are they and where can I go to verify it myself?