I use Techron in all my gasoline vehicles (7 assorted brands)every 3000 miles, change oil every 4000. Does a wonderful job of eliminating carbon and letting me use regular gas, but have never seen, nor has my in-house mechanic ever commented on a variance in oil color. I'd love to know if anyone has found a better air filter. I'm not the least bit happy with the Toyota EOM air filters, and don't have room in all engine compartments to install a double filter system. Dirt contamination is my determining factor for oil changes.