[TypeA]

The gas in the hose is irrelevant if you just plan and prepare your gas budget for a full tank, this also saves you time as you fuel less often. I suppose just a gallon or two might affect the octane rating but I doubt it, depending on hose length there is probably no more than a quart of gas in the hose. I wont get into the acceptable water content found in gasoline, knowing that might make you blow a gasket... JK I honestly think you are being concerned over nothing. The key is do you run additives? Things like Chevron with Techron helps counteract the effects of Ethanol. Several other vendors use additives, Chevron is just one example.