Abstract: An oil valve dart apparatus having a body for being inserted through two portions of an oil tank valve to prevent the two portions of the oil tank valve from moving relative to each other to thereby prevent fluid flow. A stop prevents the dart apparatus from being withdrawn one way. A seal held in a through slot near the other end of the dart apparatus prevents the dart apparatus from being withdrawn the other way. A cap is engaged to and spaced from the stop by a shaft. A tether is engaged to the shaft and a safety pin is engaged to the tether. The body, stop, cap and shaft are co-axial, integral and one-piece.