BE CAREFUL. A good friend of mine has a duramax diesel and he changes his oil @ 50% life. He was running used oil and we had a full load of round bales on the gooseneck and the truck went into limp mode due to low rail pressure due to a dirty fuel filter. I went out and changed his filter and its was full of crap, the filter had only 200hrs. on it.
Another thing the tier3 engines will not handle the crappy fuel any more. We had one run backwards in a linkbelt 330 with a 6hk1 isuzu. we found that the injector tip cracked and filled the cylinder with fuel. It had water in the fuel and the tip wouldn't pass the water drop. A tier3 injector tip has twice as many holes, but they are only half the size of a tier2