Waste oil storage tank, with double wall in polyethylene (one internal in contact with the oil and one external which serves as a spill containment and security container for the internal one). The tank is equipped with a wide dome with raisable cover. In its interior there is a removable basket for the drain of oil filters and the opening for charging and discharging the tank. At the rim of the dome a mechanical level gauge is installed that permits the control of the filling level and a transparent indicator on the side of the external tank allows to detect eventual leakages of the internal tank immediately. The tank is available in different colours for the storage of different liquids, such as mineral oils, vegetable oils, break fluid, oil-based emulsions or antifreeze.