Just pulled a 12,000 lb trailer 4500 miles with 2003 Duramax ... the last half of the trip, after running for 2 hours, the turbo would start to whine, loudly ... oscillated up and down, but seemed to pull OK ... before taking it to the dealer (who knows nothing about diesels) ... any ideas ... this will repeat itself, if you want to drive 2+ hours with a trailer ... Wayne

Are you sure it wasn't the engine cooling fan as it makes a good bit of noise? It sounds a lot deeper in tone than the turbo whistle though.Edited by: Hound