Idling

The common belief that idling a diesel engine causes no engine damage is wrong. Idling produces sulfuric acid, which is absorbed by the lubricating oil and eats into bearings, rings, valve stems and engine surfaces. If you must idle the engine for cab heat or cooling, the high idle function of the Cruise Control switches should be used. An idle speed of 900 rpm should be enough to provide cab heat in above 0°C (32°F) temperatures.