A method of filling and/or draining a replaceable fluid container for an engine or vehicle, wherein the replaceable fluid container comprises a fluid reservoir and a plurality of container ports, wherein replaceable fluid container is configured to be docked with a dock associated with the vehicle or engine with the plurality of container ports positioned on and coupled to at least one port of the dock to place the fluid reservoir in fluidic communication with a fluid circulation system associated with the vehicle or engine, wherein each of the plurality of container ports has an operational function, wherein the operational function of at least one of the plurality container ports is that of being a fluid outlet port to allow the supply of fluid from the fluid reservoir, the method comprising modifying the operational function of at least one of the plurality of container ports to assist filling and/or draining of the reservoir, a related filling and/or draining interface plate configured to interface between a replaceable fluid container for a vehicle or engine and a filling and/or draining system of a replaceable fluid container management facility and a kit comprising such an interface plate and a replaceable fluid container for a vehicle or engine.