Should I Turn Off The Car When Sitting For Long Periods?

If you let the car continue to run without it moving, it’s known as idling. The car doesn’t go anywhere but the engine stays active. Ongoing debates abound about whether idling harms the environment and your vehicle, but some cases can’t be avoided. For example, it doesn’t make sense to keep turning the car off when sitting for long stretches in traffic. Also, for anyone who drives on diesel fuel, idling actually causes exhaust fumes to clear, making the air cleaner.

How Long Can I Idle?

Technically, a car can idle as long as there’s gas in the tank, unless of course something breaks, like a fan belt or thermostat. With all systems in check, however, a vehicle will heat up like normal and continue operating until you turn it off, and since current models contain water cooling systems, air needn’t flow into the engine for adequate cooling. So, idling won’t cause the engine to overheat.

Does Idling Waste Gas?

Not really. When sitting, a car uses about 14 – 20 percent of the gas supply. Unless you regularly hit the gas pedal, it’s safe to say fuel levels will be maintained for more than 24 hours.

The Downside of Idling

Most experts agree that idling for 30 seconds to a minute causes no harm, but letting the engine run for much longer without moving can have negative effects.

  • First, a running engine emits pollution, so unless a commute warrants use, why release pollutants when you don’t have to?
  • If the car sits idle while the air conditioner runs, there’s a greater risk for carbon monoxide poisoning.
  • Irrespective of gas levels, idling for long periods can weaken the car battery, especially if the alternator isn’t working properly.
  • Never let the car idle when filling up the gas tank. With high temperatures inside the vehicle, it makes gas fumes more likely to ignite.


Some people argue that idling with the heater or air condition on keeps the cabin temperature regulated in severe weather. While this might be true for short periods, it bears noting that a vehicle running with these features on burns more fuel. Though letting the engine run for five or ten minutes won’t cause irreparable damage, make sure it’s completely necessary before choosing to idle. And if you do choose to run the engine, consider making it a rare occurrence.

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

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