The invention relates to a liquid filter, for example an oil filter for cleaning lubricating oil, especially for use in internal combustion engines of motor vehicles. A ring-shaped filter insert separates an unclean side from a clean side in the interior of the liquid filter. A metal filter housing comprises a first flange with which the liquid filter can be screwed to a component via a screw connection, said component having an inlet for uncleaned liquid, an outlet for cleaned liquid and a relatively pressureless idle duct. The first flange contains an axially acting outer seal that includes inlet, outlet and idle duct, and a carrier receiving compartment encircled by the outer seal. A functional carrier insert is inserted in the carrier receiving compartment and is provided with an inlet compartment open towards the inlet, an outlet compartment open towards the outlet, and a idle duct compartment open towards the idle duct, the individual compartments being sealed from one another by axially acting inner seals. The screw connection with which the first flange is screwed to the component acts in the axial direction and axially forces the axially acting seals against the component, while the functional carrier insert rests on the first flange.