Let me chime in as a pennzoil lube shop manager, Conventional oil that you buy off the shelf is around 80% oil and 20% additives. .after around 3000 miles the additives in the oil are at or nearly at full contaminant capacity. Just like the filter, the additives are designed to invade and trap dirt, carbon, acid, and other contaminants so they can be drained out. . All used oil from quick lubes around the country is recycled and used for heat or asphalt and such. .all Valvoline is doing is re-refining it. .it goes through the same distilling and flashing process that crude goes through. Only difference is it starred out as oil and not crude. .crude has some of the same contaminants as used oil does before its refined. .its not harmful at all. I have a Pennzoil meeting tomorrow with clayton and the guys from pennzoil. .joy!! They let us in on stuff like that at these meetings, discuss new products and discuss science behind it all. .Sometimes boring but hey we get free dinner at a nice restaurant!!