Originally Posted by Socalken
one of my good friends is a service manager at a local dealership 4 GM.we talk all the time about different motor trans combinations. There's no way this motor goes 300,000 miles. Like I said 99% of them are dead 125,000 miles. But I'm sure there's one or two that make it that long if you baby it and don't tow with it. But I guess the exception proves the rule.
Your friend may be correct. But I personally know of 3 fellow commercial fisherman that have 250K+ on their 6.0 engines, and they were not babied. It also gets very good reviews on forums like this one, http://www.silveradosierra.com/
The more recent (2007-2012) 5.3 AFM equipped engines have a tendency to burn oil, and that has been a great subject of discussion there.