The turbochargers in various diesel trucks may require idling a truck for a few minutes in order to allow the turbo to slow down and cool, protecting bearing components. The need for idling will vary based on the age and model of the truck, as well as the amount of weight the vehicle has been pulling.
Long-term idling can cause more wear and tear on diesel motors than driving at normal speeds. By leaving a motor running for longer than necessary, not only do you risk eventual damage, but you use excess fuel and produce unnecessary emissions.
Allow a turbo diesel truck to idle for cooldown according to the vehicle's manufacturer's specifications. The normal recommended time frame for idle before shutoff is three to five minutes, depending on how long you have been driving the vehicle and if it has been towing. There is no need to idle a diesel truck for any period of time beyond the initial cooldown.
