Whatever the manual says to do. Oil changes at 3K miles using dino oil is a thing of the past and is a ploy by the oil companies to help them make more money. I also believe it's just a waste of resources as well. Oil manufacturing and oil additives are far more superior than when compared to your dad's or grandfather's days when they were driving. Tolerances in engine building are much better too. With newer cars and trucks, I've seen change intervals at 7.5K with dino oil, specified in the owner's manuals. They have extended intervals because vehicles are made better these days, not because the car companies want their cars to breakdown faster as you put it. What car company wants to have that reputation? <img src="/forums/images/graemlins/confused.gif" alt="" />