Does Idling in Place Harm the Car?
4 Answers
Idling in place can have certain effects on a car. Prolonged idling can lead to increased fuel consumption, and since the engine does not burn fuel completely during idling, it can produce more carbon deposits, thereby accelerating engine aging. When the engine is idling, there is a significant amount of residual exhaust gas in the cylinders. To ensure stable combustion, the car will automatically enrich the air-fuel mixture. During idling, the oil pressure in the engine is relatively low, which worsens the lubrication condition of moving parts. Unburned fuel washes the cylinder walls, the intake vortex is weak, and fuel combustion is incomplete, making it easy to form carbon deposits. When carbon deposits accumulate to a certain extent, the car's power performance will decline, and over time, it can easily cause engine wear.
I think idling in place depends on the duration. Having driven for decades, short idling like waiting at traffic lights or temporary parking for a few minutes really isn't an issue. But prolonged idling, especially over half an hour, is indeed not car-friendly. The engine running at low speed for long leads to incomplete fuel combustion, causing carbon buildup—particularly in the intake tract and throttle body, which are prone to clogging. Over time, fuel consumption also sneaks up since the engine burns fuel without doing much useful work. The worst part is the strong exhaust fumes, especially in winter when parked underground—the smell can give you a headache. If I have to wait, I turn off the engine and step outside; fresh air beats sitting in the car wasting fuel any day.
My personal habit is to avoid idling the car in place except when waiting at traffic lights or temporarily pulling over. Idling with the air conditioning on in summer is the most damaging to the engine, as it puts a heavy load on the cooling system and easily leads to carbon buildup. I've seen a friend's car shake violently like an asthma patient during cold starts because they often idled with the AC on—the mechanic directly pointed out that the piston rings were stuck due to carbon deposits. Moreover, the catalytic converter operates inefficiently when kept at low temperatures for extended periods, making it particularly prone to triggering the check engine light during emissions tests. With fuel prices so high these days, burning gas while stationary is simply a waste of money—far better to turn off the engine and grab a coffee instead.
Having disassembled engines for repairs, I've seen too many cases. For vehicles that idle for extended periods, engine oil deteriorates at least twice as fast, with visible sludge layers on cylinder walls. It's like a person lying down all day without exercise – slow blood circulation easily leads to thrombosis. The anti-wear components in engine oil are also consumed faster, accelerating wear on camshaft and lifter surfaces. Veteran drivers often say cold starts cause significant wear, but idling conditions are actually more hazardous for vehicles. Experimental data shows that one hour of idling equals the wear of driving 30 kilometers on highways. If I need to wait for someone for more than 10 minutes, I'll definitely turn off the engine and take a walk.
