Hi guys really need someone who knows 2.0TDI BKD engine inside out. Had my 2.0 TDI S line quattro since new in Dec 2005 first 22000 miles all was well until Turbo started whining like I was being followed permanently by a police car.This was replaced under warranty. All well again until new turbo failed with overboost issues (vaines sticking) having only done 14700 miles car was just out of warranty but due to length of time turbo had been fitted Audi fitted another turbo as a good will gesture. This is where I need help 3rd Turbo failed again with overboost issues (sticking vaines again) having done 11600 miles. Audi say the turbo's failed due to too much soot causing veins to stick exactly same fault as previous turbo, surely there is some underlying problem causing this anyway Audi fitted another turbo free gratis as they say it shouldn't have failed in that mileage! New turbo was fitted and Audi had the car a week to ensure there was no underlying issue causing the turbo's to keep failing. They couldnt find anything at all and I got my car back again, this was last Wednesday I had the car back 1 day and the new turbo failed again whining its head off. Car went back in on Tuesday this week for its 5th turbo fitting. got my car back now but have a problem with smoke when starting the car. When I first start the car for first few seconds car doesnt want to idle properly then it clears and idles normally but then I get grey smoke bellowing from exhaust till it clears. I returned car back to Audi to see if they could resolve starting/smoking issue, only to be told they don't know whats wrong with it. If anyone has got any ideas or could explain what could be causing turbos to keep failing or the starting smoking issues please respond. The car has done 47780 miles always been serviced by Audi dealer and run on Shell diesel.