I was just thinking about this. Can't believe I didn't mention this before. At the prison I work at we have a perimeter vehicle that circles the prison 24/7 (when its not in for repairs) at no more than about 20mph and less than 1000RPM on average for engine speed. The vehicle is a 2003 Dodge Ram Cummings Turbo Diesel... the oil is changed every 3K and one lap around the perimeter is about .7 miles. I'd love to see an analysis of this oil... anyone else care to take a stab at what kind of problems we'd see in an sample of this oil?