We recommend filling the tank with fresh fuel before storage to displace the air. The tank will still breathe slightly, but the water incursion will be very small. Before filling the tank add Gumout® Multi-System Tune-Up to prevent fuel oxidation (gum and varnish) and corrosion protection (rust and pitting). Run the vehicle to deliver treated fuel to the fuel line and carburetor so these areas are stored in contact with the protective chemistry. Multi-System Tune-Up is an excellent fuel stabilizer.