I am in no way an engineer nor do I want to start a debate about synthetic vs organic oils as they apply to mileage that usually consume a board.
But I will give my two cents on why I achieved such relatively great mileage during my trip.
1. Used cruise control for most of the trip.2. I think the VQ motor is most efficient at around 3000 rpm and since our average speed was 80 mph, the engine was working efficiently most of the time.3. The air was cooler in the northwest as supposed to Sacramento (where I live) where in the summer it's usually 100+ with little humidity. So I guess the fuel management computer was working well.
That said, as soon as I got back to Sac, my mileage dropped since I commute at night and can do 90+ on my way to and from work. It's amazing what 500-1000 rpms can do for one's mileage!
I guess once Georgie goes to war and the oil companies jack up their prices because of oil market "unstability", I will drive 55...