Columns | Daily Chronicle

Honeywell: Idling too long? Here’s why it’s bad for you and your car in winter

Editor’s note: This is the January installment of a monthly column written by the city of DeKalb’s Citizens Environmental Commission that focuses on increased awareness of issues such as promoting projects and ordinance changes involved in recycling, reducing energy consumption, and planting native habitat.

It seems that the weather can’t make up its mind these days.

We’ve gone from what felt like polar temperatures to early spring in a matter of a couple of days. We can expect the weather to turn cold again before spring.

When things become that terribly cold, it’s tempting for us, when we are forced to go out, to let our vehicles idle for several minutes before driving. Part of the practice of letting our vehicles run a bit comes from a sincere desire to protect our engines.

The thinking is that when it is that cold out, it’s potentially damaging to engage our engines right away. To be honest, though, most of our insistence on idling our vehicles comes from our own comfort. It’s not fun to be in an ice-cold car.

The truth is that excessive idling of your car is problematic for a number of reasons.

First, there is the environmental issue. As far back as 2009, an energy sector study determined that as much as 1.6% of U.S. greenhouse gas emissions came from vehicle idling, and nearly half of that from cold weather idling. While the current efficiency of vehicles has likely reduced this number, idling is still essentially running the engine and not going anywhere.

A second factor is fuel waste. For vehicles that are less than 30 years old, no more than 30 seconds of idling is needed to warm the engine enough to drive it safely, and driving gently for the first 10-15 minutes is the best way to warm the engine up fully. Leaving the car idling for as little as 5 minutes can increase fuel consumption by as much as 14%. For extremely cold days, it can be worthwhile to idle for a full minute before driving, but more than that is unnecessary.

The third important factor is potential damage to the car’s engine. If the mix of air and gasoline is not ideal, excess gas can strip the engine of lubricants, increasing both the rate and amount of wear and tear on the engine. This seems counterintuitive, especially with the thought that more engine warmth is needed for engine oil flow. However, modern engine oils have been formulated to work at temperatures as low as negative 40 degrees.

To be fair to the pro-idling people, cars do tend to be less efficient at lower temperatures, and with more intense cold, it does take longer for cars to heat up to a more efficient temperature. This is why driving the car more gently at the onset is important. This is also going to be different for older models of cars.

These facts about idling are not only true when it comes to cold weather. Idling your car, for instance, in a drive-through, can use between a quarter and half gallon of gas per hour. Parking and going into an establishment rather than waiting in the drive-through could save a substantial amount of fuel and significantly reduce emissions.

Please visit the Citizens’ Environmental Commission at and the City of DeKalb Facebook page. Have a wonderful, sustainable 2023!

  • Steve Honeywell is a member of the city of DeKalb’s Citizens’ Environmental Commission.