Does it hurt a car engine to run idle?

In short, yes, it can hurt a car engine to run idle for extended periods of time.

Why is idling bad for your engine?

When your car is idling, the engine is running but the car is not moving. This means that the engine is not getting the proper amount of airflow, which can lead to a number of problems, including:

Increased carbon buildup: When the engine is not getting enough airflow, the fuel does not burn completely, which can lead to the buildup of carbon on the pistons, valves, and other engine components. Carbon buildup can reduce engine power and efficiency, and can also lead to premature engine failure.
Oil dilution: When the engine is idling, the oil is not circulating properly, which can lead to oil dilution. Oil dilution occurs when fuel seeps into the oil, which can reduce the oil’s viscosity and effectiveness. Oil dilution can lead to engine wear and tear, and can also increase the risk of engine failure.
Battery drain: When the engine is idling, the alternator is not generating as much power as it would if the car were moving. This can lead to battery drain, which can make it difficult to start the car.

How long is it OK to idle a car?

The amount of time it is OK to idle a car depends on a number of factors, including the age of the car, the condition of the engine, and the outside temperature. As a general rule of thumb, it is best to avoid idling for more than 30 minutes at a time.

What should you do if you need to idle your car?

If you need to idle your car for an extended period of time, there are a few things you can do to minimize the risk of damage:

Keep the engine speed high: When you are idling, keep the engine speed at around 1,500 RPM. This will help to keep the engine from building up carbon and oil dilution.
Use the air conditioner sparingly: The air conditioner can put a strain on the engine, so avoid using it when the car is idling.
Turn off the lights: The lights can also put a strain on the engine, so turn them off when the car is idling.
Take breaks: If you need to idle your car for an extended period of time, take breaks every 30 minutes or so to let the engine cool down.

Conclusion

Idling your car for extended periods of time can hurt the engine. If you need to idle your car, keep the engine speed high, use the air conditioner sparingly, turn off the lights, and take breaks every 30 minutes or so to let the engine cool down.