It's very convenient for me to fill up any time I want as I pass by two gas stations everyday. Should I fill up when I'm bone dry empty, 1/4th tank, half, 3/4th tank? When is best to fill up? I heard it's easier on the pump when your tank is mostly full and you save gas that way too plus leave less room for water vapor to get in. However, aren't the gas savings offset by hauling around the extra weight of the gas all the time? Does running empty all the time kill the pump and cost more than savings you'd obtain in gas from not hauling around 200+ lbs of gas?