A magnetically enhanced oil filter apparatus includes an open-ended cartridge housing which includes means for connecting to an engine block, inflow ports for receiving oil flow from the engine block, and an outflow port for sending filtered oil to the engine block. A block-to-housing sealing gasket is connected to the open-ended cartridge housing for providing a seal between the open-ended cartridge housing and the engine block. Direction control baffles are housed inside the open-ended cartridge housing for directing inflow oil for magnetic treatment and for directing magnetically-treated oil to the outflow port. A cartridge-housing lid, a lid-to-housing sealing gasket, and a magnet assembly unit are provided. A peripheral clamping assembly is provided for clamping the magnet assembly unit, the lid-to-housing sealing gasket, and the cartridge-housing lid to the open-ended cartridge housing.