I have a 2006 mega cab with the 5.9 cummins. I just turned 33,000 miles on the truck, and just noticed it will puff a little white/gray smoke when started inthe morning.It won't do it if the truck is still warm. Only when it sits for a while. Should I be concerned?

 

If it is one little puff and no other symptoms I would not worry much. If it continues to white smoke for a minute or so, runs rough, and fuel economy starts falling then you probably have an injector problem.

 

that's completely normal for a cold motor. The block is cold, and the incoming air is cool. It's the compressed hot air that ignites the fuel so, until it warms up, unburnt fuel will get by.