oops .... forgot to change the oil

afidel wrote:

midnightsadie wrote:
I,m not for anything over 10k for a oil, and filter change, I don,t like all that nasty looking oil going threw my engines,

We short changed the wife's minivan when new, next one we decided to go with the oil quality indicator, took 12k miles before it came on. When we had the oil changed I had a retain sample taken, it still had a nice ruby color, almost no black, lab said it still had a bunch of additive life left and the oil itself was in good but not great shape. Since then I have stopped worrying about it and just follow the idiot light. My car is older (04) so I follow the manufacturer's 5k mile recommendation but don't worry if I go a few hundred or even a few thousand over. The truck also gets 5k mile changes with full synthetic due to the much heavier duty cycle of 90% towing.

We own heavy equipment that works in extreme dust conditions at 75-110% engine load all day long. To put it another way a 500 HP engine in these applications goes through about 250 gallons of fuel in a 10 hour day. The manufacturers of this equioment recommend oil change intervals of 600 hours using dino oil..... to say it another way ... every 15000 gallons of fuel. These engines have a large oil capacity of 40 liters. So your Duramax with a 10 liter sump should probably be changed 4x as often ... So every 3750 gallons of fuel when it's working very hard. To work your engine hard you would have to tow your trailer at 90 mph where you might get 6 mpg. 6 mpg x 3750 gallons works out to 22500 miles with dino oil.