When it is necessary to leave the engine on in cold weather, idle settings should be based on what?

The correct approach for determining idle settings when leaving the engine on in cold weather is based on departmental Standard Operating Procedures (SOPs). SOPs are established guidelines that inform personnel of the best practices within their specific department, which may take into account various factors such as safety, engine performance, and efficiency.

Utilizing SOPs ensures that practices are consistent among all personnel in the department and are tailored to the specific equipment and operational environment of that department. These procedures are typically developed based on collective experience and industry best practices, making them a reliable source for guidance.

While manufacturer recommendations and the type of engine used are important considerations, they are typically integrated into the department's SOPs. Personal preference might not align with the best practices needed for optimal engine performance and safety in cold weather conditions. Thus, adhering to your department's SOPs provides the most appropriate and standardized method for managing engine idle settings in these circumstances.