In most instances, prolonged engine idling is an unnecessary waste of fuel. During normal engine start up, idle the engine only until the engine oil reaches operating pressure as indicated on the dash gauge. When shutting down at the completion of normal highway driving, usually the slower speeds of exiting the highway have provided ample engine cool down time.

The common belief that idling a diesel engine causes little or no damage is a misconception. Extended idling can in fact produce sulfuric acid that breaks down the 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 feature of the cruise control switches should be used. Idle speed of 1100 RPM should be adequate to provide cab heat in above 32 degrees ambient temperature.

Turbo works for the engine similar to the way adrenaline works in the human body, and is necessary to enhance fuel efficiency and emissions performance. In the early days of turbochargers it was necessary to wait for the turbo system to build up and provide the needed boost of charge all at one time. Modern day turbochargers are electronically monitored to deliver controlled power over time.

The turbocharger used on the Detroit system is known as a VNT (Variable Nozzle Turbocharger). Designed with the ability to open and close the turbine wheel vanes, the VNT provides boost pressure that is modulated for current performance and emission demands. The VNT is also a key element for Exhaust Gas Recirculation (EGR). For the RV operator, this means minimal lag when climbing a long hill under a heavy load.

Engines naturally lose power in higher altitudes due to decreased oxygen in the air. A turbocharger is installed to make up for the lowered air pressure of high altitude and propel the engine upwards at a steady rate of speed when the RV is pulling a high grade, such as 6%. During the climb the turbocharger heats up, and if the engine is turned off at this time the bearings can overheat and cook the oil. If you pull over to the side of the road immediately after pulling a steep grade, raise the high idle feature for 4-5 minutes.

When using the Smart Wheel for high idle, follow this technique:

Turn the cruise control on by pushing the on/off button one time. The icon in the dash should read 'cruise.'
To raise the high idle, touch and press the resume switch one time. This will raise the idle to about 850 RPM.
If you prefer to raise the fast idle a bit higher, with the cruise control still on, press the resume and set buttons together to resume the idle at a desired speed.
In compliance with the Detroit Diesel Engine operator's manual, perform a daily visual inspection for leaks at the turbocharger mountings, as well as the intake and exhaust ducting and connections. Because the oil line runs from the side of the oil filter housing, up to the top of the turbocharger in the center to lubricate the bearings, the turbocharger can heat up enough to burn off leaking oil.

During your pre-drive walk around, check under the RV for any sign of oil on the ground, or coming down the side of the block. Oil at the back of the tailpipe may be the result of build up in the exhaust system from extended periods of idle.

Don't worry if the engine experiences a slight lag when pulling into traffic from a complete stop. In order to comply with mandated EPA regulations to eliminate black smoke produced when taking off from a complete stop, updated engines have incorporated a Smoke Control Lag.