A method and apparatus for cleaning, and removing contaminants from the interior of a lubrication rundown tank of a mechanical system provides a source of pressurized and heated cleaning fluid containing at least one solvent; a first jumper hose communicating between the source of pressurized cleaning fluid and the interior of the lubrication rundown tank; a second jumper hose communicating between the interior of the lubrication rundown tank and a dirty fluid collection body; and an outlet spray nozzle carried by a nozzle extension placed within the interior of the lubrication rundown tank and in fluid communication with the source of pressurized and heated cleaning fluid to receive the pressurized and heated cleaning fluid therefrom.