A method and system for replacing used oil in a vat, the system including a nozzle having inner and outer concentric passageways, the outer passageway being connected to a supply of replacement oil, pumps associated with each of the inner and outer passageways, with a valve structure and a nozzle, the valve structure having biasing means. The system is suitable for pumping hot oil from a vat such as used in commercial kitchens to a storage receptacle and subsequently pumping replacement oil into the vat.