At long last, the cold weather has finally swept over the United States. That means Americans from coast to coast will be forced to summon their vehicles from chilly morning slumbers before making the commute to work.
Before you turn over that engine, though, have you considered whether or not you should let the engine idle before driving away? Today, we answer the fundamental question: How long should you warm up your car in the winter?
Separating Myth From Reality
The short answer: 0 minutes.
Now, we know what you’re thinking: That’s crazy! Won’t you damage your engine?
For nearly 12 decades, it was believed that a conventional gasoline combustion engine needed to idle before putting the transmission in “drive.”
The reason behind this phenomenon was that the oil within the engine needed to warm up so that it could adequately spread throughout the engine, thus reducing the chance of causing damage to the internal moving components as the vehicle accelerated to road-appropriate speeds.
Fact 1: An engine running at higher RPMs (such as when the vehicle is in motion) creates more heat than an idling engine. Therefore, if the sole purpose of idling is to create heat, it is best to avoid keeping the vehicle parked while running.
Fact 2: Idling your engine actually has adverse affects on your oil’s lubrication properties. The longer your vehicle idles, the more raw gasoline escapes from the injectors and spills into your engine’s oil, thus breaking down the oil molecules. With your oil’s structural integrity compromised, engine wear will occur much faster over time.
Fact 3: Idling an engine for even just 10 minutes each morning will expend up to a quarter of a gallon of gas; add this up between cold morning idles, sitting at stoplights/stop signs, waiting in traffic, grabbing lunch at the drive-thru and picking up someone from work or school, a vehicle could reasonably idle away several gallons of gas per week.
Fact 4: The main reason society believed engines needed to idle in the cold before driving away actually came from the carburetor era. Before fuel injection systems, carburetors needed to be warmed up in order to smooth out the vehicle’s power band, making them easier to drive. Today, fuel injection and your engine’s Electronic Control Unit (ECU) regulates the power band automatically, regardless of outside temperatures.
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