Depends on whether you're on a hill and in which direction it slopes. That's a long-ašš fuel tank and the pump will suck air when the gas runs to one end. I never let mine get below a quarter unless I'm out in the boonies to reduce wear and tear on the fuel pump. Sucking air is really hard on them.I looked but couldn’t find a definitive answer…. When The gas light is on does anybody know the amount of gallons left in the reserve?