Abstract: A lubricated wing nut device for attaching a cover plate to a container such as on a gravity tee of the type used for closing a discharge hopper of a tank transport vehicle. The lubricated wing nut inhibits corrosion and seizing of the bolt used in securing the cover plate to the container opening. It comprises a cast metal body having a longitudinal bore of a predetermined diameter inwardly from a base end thereof. Fitted into the bore is a stainless steel nut having an internally threaded surface for engaging the threads on a bolt. The longitudinal bore is adapted to be filled with a lubricating grease.