Abstract: There is disclosed a refueling system and method for simultaneously refueling the fuel tanks of multiple pieces of machinery in the field. In an embodiment, the system comprises a mobile tanker with at least one fuel supply tank configured to connect and supply a plurality of refueling hoses. Each refueling hose has an upstream end connected to a supply line from the at least one fuel supply tank. At a downstream end, each refueling hose terminates at a mechanical open-close valve which is adapted to be inserted within each receiving fuel tank being refueled. The mechanical open-close valve is suitably shaped and sized to provide a clearance fit within the neck diameter of each receiving fuel tank being refueled, and has a buoyant body for mechanically actuating the mechanical open-close valve.