I change when the "message center" on the dash tells me to. Usually when it says "oil life remaining 5%" or less. I run recommended weight synthetic in everything. When I had vehicles that did not have the oil monitoring feature I changed at 6-7,000. I ran synthetic then, also. Can't complain. Had a Grand Caravan that had 175,000 on it when I got rid of it. The only engine work ever done on it was new spark plugs and wires a couple of times. My brother was a great believer in Mobil 1. He had a Toyota pickup that had 250,000 on it when he quit driving it. His reason for replacing it was that the rear main started leaking and he didn't want to pull the engine to fix it.