I am looking at used Durangos. i looked at one and when I started it cold, blew out white smoke from the exhaust. I also noticed the coolant resivoir was empty, though the radiator was almost full. How common are intake gasket leaks on these things? It's a clean truck with 128,000 miles and no apparent problems other than the white smoke. It wasn't horrible, but looked like more smoke than should be there.