I have a 2006 LLY engine it has 75,000 miles on it I bought it at a dealership and it is a certified vehicle. When you turn the vehicle off you can here the turbo turning for about 15 - 20 seconds and it sound like a bad bearing noise. "growling noise" I took it back to the dealer and the tech said that was normal? I have about 3000 more miles till the warranty is out. Just wanted to know if anybody has the same noise and what the fix is. I have heard other duramax engines and they do not make that noise. Thanks for your input.