Q: How long should I warm up an engine?
A: This depends on how cold it is outside, but generally about 15 – 30 seconds is sufficient to get the oil circulating. After that, you are wasting fuel and adding pollutants to the air. Many states have anti-idling laws. In addition, you shouldn’t leave your vehicle unattended when it is idling. After 30 seconds or so, accelerate slowly. Driving the vehicle in a moderate way is the best way to warm it up. The only rationale to idle longer would be to clear the windows for visibility if you couldn’t get them clear with an ice scraper.