On a related note, don't start your machine and let it idle in the driveway (not that you do, but just in general). As soon as you have oil pressure, its good to get underway (mellow). An idling engine will take much longer to reach operating temperature than one that is driven easily (no full throttle, high revs, etc.) The quicker the engine reaches operating temperature, the less blowby, the less acid formation in the oil. I see all kinds of people around here letting their cars idle for ten minutes or more on cold mornings, thinking that they are doing their cars good...

The cool down period for a turbo is definately important. I know that it is a bit of a pain when I'm driving my cummins unit and want to run in to the grocery or beer store, but I've tried to be pretty strict about letting it run for at least a minute before shutting it down. I'm going to wire in an ignition switch that reads temperature from the pyrometer and allows the engine to run after removing the key until exhaust temp reaches a safe level. Maybe you turbo guys could do the same...