[cole930]

You might take a look at the turbo drip tank circuit, it sounds like you may be getting too much oil to the turbo or oil running back to the turbo after shut off. There are good threads here on this. Check to see if there is a 9mm ball bearing inside the fitting under the oil pressure sender at the back of the motor, top side. This ball bearing acts like a check valve so when the engine is shut down oil won't continue to siphon into the turbo. Check the opening in the turbo through to the drip tank, the drip tank, and the line all the way back to the scavenge pump on the back of the drivers side cam box, there may be coking or an obstruction. You can also take the oil line from the scavenge pump off at the drip tank and put the end in a shallow pan of oil, start the engine and verify the scavenge pump is pulling properly. If the ball bearing is missing I just got some last week. Good place to start, as symptoms your seeing are the same as this issue smoking a little on start up and then getting progressively worse until the turbo seals fail.

Cole