Idle I Warm-up I Cooldown
Excessive Idle
Should be avoided when possible. Results in reduced fuel economy and increased engine wear. An automatic shutdown feature is available. Contact a Cummins distributor for details.
Engine Warm-up
Do not operate at full speed/load until coolant temperature reaches normal operating range. Do not operate above low idle until oil pressure is indicated.
Engine Cooldown
Prior to shutdown, an engine should be idled 3-5 minutes after extended full throttle or high power operation. However, under normal driving conditions, such as exiting a highway, engine operation is generally lighter in nature and thereby, the 3-5 minute cooldown is not necessary.
http://www.cummins-sp.com/support/rv_maintenance_operation-isc.htm
