I work my '06 Cummins Dually 7 days a week.It has 404,000 miles with the OEM waterpump on it.I have never had the valve cover off and I change oil every 5,000 miles.I bought the truck used in 2010 with 21,000 miles on it.I run over 100,000 miles a year hotshotting to the oil and gas rigs.I was above Dubois, PA yesterday and will be in OH today...love my job!!