Can Your Car Idle Without Damage? Find Out Now!
How Long Can Your Car Idle Without Damage?
Because of push-button start mechanisms, forgetting to shut off your engine is becoming more common. In the old days, it was easy to shut off your engine because you needed to remove the key from the ignition switch. But with push-button ignition and quiet engines, you can put your car in park, leave, and forget your engine is still idling. So, how long can your car idle without damage? There’s no definitive answer to this but there are some things you can do as soon as you find out you’ve let your engine idle for long periods
Extended Idling Is Harmful
Air pollution and fuel economy issues aside, idling for more than 20 minutes can be harmful to your engine, especially if it’s equipped with a turbocharger. Worse yet, if your engine’s oil level is even a quart low, you run the risk of serious damage due to extended idling.
• You have lower oil flow at idle RPMS — When you idle your engine, there’s little load in the bearing areas. But that doesn’t mean you’re in the clear to let it idle for hours. The opposite is true: Hours-long engine operation at idling speed can be extremely harmful to the engine because a low RPM means there’s lower oil pressure and less flow.
When your engine runs at driving speeds, the crankshaft and camshaft rotation spin oil out of the bearings, allowing fresh oil to remove heat from the bearing areas. However, at low RPMs, there’s less oil spin-out. When you combine the effects of less spin-out with lower pressure and flow rates, you set up the conditions for bearing wear due to heat and loss of lubrication.
•Lower RPMS means less oil splash or less jet spray—In many engines, oil splash saturates the oil control rings. However, many late-model engines rely on oil jets that spray oil onto the pistons and the oil control rings. Lower RPMs, lower pressure and less flow can reduce the effectiveness of both oil splash and oil spray.
• Idling in hot conditions cooks the oil— Engines run about around 200°F and once they’re at operating temperature, the oil is also around 200°F. When driving, your oil is cooled by airflow across the oil pan. But you lose that cooling when your car idles for long periods.
Oil breaks down due to heat, oxidation, and contamination. Engines that idle for long periods generate carbon deposits in the cylinder head, oil control rings, and intake valves.
What to do if you forgot to turn off your engine
Let’s say you forgot to shut off your engine and it ran overnight. If you did just one time, you probably didn’t cause serious damage. But you should immediately get and oil change.
Get an oil change ASAP—The long idle has most likely depleted the anti-oxidant additive package in your oil, as well as caused some oil viscosity breakdown.
Get your next oil change sooner than normal— The reduced oil change intervals will help clean any carbon deposits that may have formed during the extended idling.
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