Welcome Bob..... One little side note. I don't know if you have a GXP or not... But they REQUIRE Mobil1 full synthetic oil. NEVER, NEVER, NEVER use conventional oil in them!! If you have a GXP and you use conventional oil, you will be replacing your turbo in 500 miles.
That's a bit of an over simplification.
The turbos are water cooled. While they are running, no harm comes to the centre bearings.
If you idle them down before shutting them off no harm comes to the bearings.
If you end a hard run (say, up the hill to your house) and then kill the engine before idling a bit, the oil may get hot enough to cause ash formation in the bearing, which definitely will damage it in pretty quick order.
GMs answer to this was to specify a synthetic oil with excellent anti-ashing qualities. Other cars run such things as 'turbo savers' that hold a small reservoir of cool oil that runs through the bearing after shut down - no synthetic needed in that case.
You CAN run a turbo engine for years without any damage if you know what you are doing. GM (rightly) assumed that people are too dumb to do that so they mandated synthetic oil to avoid warranty claims (they could have gone the oil reservoir route but that would have been a production cost to them, whereas the synthetic oil is all paid for by the buyer of the car).