How Long Should You Let a Car Warm Up in Winter

When it gets frigid outside, common wisdom says you should warm up the car before driving it. In fact, a 2009 survey found that most Americans believe you should idle an engine for at least 5 minutes before driving in freezing temperatures. Unfortunately, this advice is outdated and inaccurate. Here’s why warming up your car in winter does more harm than good.

A Combustion Engine

Your car’s internal combustion engine functions by using pistons to compress air and fuel inside a cylinder. This mixture then ignites and creates an explosion that powers the engine. When the engine gets cold, gasoline evaporates less, negatively-affecting the air-to-fuel ratio. To compensate for this imbalance, modern cars have electronic fuel injectors that use sensors and pump extra gasoline, as needed.

A Carbureted Engine

Since carbureted engines dominated the roads prior to the 1980s, the idea of warming up the engine in cold weather comes from that time. Unlike combustion engines, carbureted ones combine air and gasoline to run a vehicle, but lack sensors that add extra gasoline to the mix. Because of this difference, older cars do require warming up when cold weather sets in.

How Warming Up the Engine Can Cause Damage

When you run a cold engine, you’re essentially adding extra fuel to the combustion chamber, and some of it can get onto cylinder walls. Since gasoline acts as a solvent, it can wash away the cylinder’s much-needed oil, removing lubrication from these heated components. If this happens, the lifespan of cylinders and pistons can be reduced, and the engine will likely consume extra fuel to compensate for lost lubricant.

What to Do Instead

The best way to warm up a cold engine is to drive it, and experts recommend setting off no more than 30 seconds after starting the ignition. Once internal temperatures reach 40 degrees, the ratio of air to fuel will normalize and all will be warm. And although warm air generated by the heater will flow through the cabin, the damage idling can cause to the engine doesn’t justify the added comfort.

When winter weather strikes, simply follow safe ice-removal procedures, check to make sure the defroster works, and get going. To stay safe while your engine warms up, start slowly for the first 5 to 10 minutes, as excessive acceleration can strain a cold engine.

For all your vehicle’s repair/maintenance needs, call Meadows Automotive in Waterford today!

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