Over the weekend I did a mileage check. Took the family on a mid winter weekend vacation. Over exactly 100 one way miles of driving in 15-20F temps at 75 to occasional 70mph I got 38.4mpg. Auto trans four door 2008 loaded down with family and gear for three days. Never had it do that good.

only things I did different was 3.000 miles ago I put seafoam in the oil and (directions followed to the T) drove it 100 or so miles then changed to valvoline full synthetic high mileage. I also did a seafoam to the gas a couple tanks before the trip. The car has a total of 99,500 miles.

nothing else has changed. I know the seafoam made it run more smooth and it had to clean out the fuel system as well. The oil might make a small difference but that's 4.1 mpg better than every other trip it went on.

Just thought I would throw it out there that seafoam clean in the oil and in the gas works if you follow the directions. The oil may have made a difference but like I said. Oil won't makthat huge of a difference.