Myths & Facts

Many people think that you should idle to warm your engine. Others will tell you that starting the engine uses more fuel than idling it. The truth is there are a lot of myths about idling. While some of these myths used to be true, advances in engine technology have made idling unnecessary. Below we dispel some of the most common myths about idling.

Myth: Idling is good for your engine.
Fact: Excessive idling can actually damage your engine components, including cylinders, spark plugs and exhaust systems. Fuel is only partially combusted when idling because the engine does not operate at peak temperature. This leads to the buildup of fuel residues on cylinder walls that can damage engine components and lower mileage.
   
Myth: Each time you start a vehicle you waste more fuel than if you let it idle.
Fact: Engines don’t operate efficiently when they idle. Experts say that the break-even point is 10 seconds. Idling longer than 10 seconds, wastes more fuel than turning off the engine and restarting it.
   
Myth: Vehicles should run in an idling mode for several minutes before being driven, especially on cold days.
Fact: Modern gasoline engines don’t need more than a few seconds of idling time before they
can be driven safely. In fact, the best way to warm up a vehicle is to drive it, since that warms up the catalytic converter and other mechanical parts, in addition to the engine. Modern diesel engines require no more than 3 minutes of warming.
   
Myth: Idling doesn’t waste much fuel.
Fact: An hour of idling time in a 4-cylinder vehicle uses more than a gallon of gasoline and more than 4 gallons in an 8-cylinder vehicle. In a diesel vehicle, idling for an hour consumes approximately a gallon of fuel.
   
Myth: Repeatedly restarting your car is hard on the engine.
Fact: Frequently restarting your vehicle does no more damage to the engine than normal use. In fact, idling an engine forces it to operate inefficiently and can reduce engine performance and fuel efficiency over time.