I have decided to do something that the military does and alot of fleet owners do. I will change the oil when the lab says it is time. My brother drives a 18 Wheeler and they do oil changes only as needed. Filter changes however are done normally, I think there are 3 types of schedules they use. So Ia m going to apply that to my truck and see if it works. This is the 3rd sample I sent off and the others were normal....do you think I am screwing up by doing this?