A method for controlling fluid distribution in a fluid circulation system associated with an engine, the fluid circulation system being coupled to a replaceable fluid container comprising a fluid supply port configured to couple to a fluid supply line of the fluid circulation system, and a fluid return port configured to couple to a fluid return line of the fluid circulation system, and a breather port configured to couple to a breather output of the fluid circulation system, the method comprising causing the fluid to flow into the replaceable fluid container from the fluid circulation system whilst inhibiting outflow of the fluid from the replaceable fluid container into the fluid circulation system, so as to collect the fluid in the replaceable fluid container, and related apparatus configured to control fluid distribution in a fluid circulation system associated with an engine, and causing a gas to flow from the replaceable fluid container through the breather port whilst inhibiting outflow of the fluid from the replaceable fluid container into the fluid circulation system.