Ridgerunner29 wrote:
I have a 2012 2500HD with a 6.0 (36,000 miles) and have never experienced the problem you describe. I believe the 6.0 2500HD's from 2011 through 2014 have a very very similar engine, drive train, frame, and suspension (this is information I got from a video review I recently watched ).
Good luck with your truck. I have been very happy with mine.
Receiving a letter acknowledges the fact that certain environmental events may lead to longer crank times. Maybe it is a design flaw and will be corrected. At least as of now this is acceptable to GM and it sounds like the OP is satisfied. It sounds like other than the crank times being atypical with what the OP was expecting no other issues.