Oil filters are critical engine components responsible for removing contaminants from circulating engine oil. Typically located within the engine oil pan or filter housing, they prevent abrasive particles from damaging bearings and other internal components. Construction utilizes a pleated cellulose or synthetic filter media to maximize surface area and capture particles as small as 20 microns. Filter housings are constructed from steel or aluminum and incorporate internal bypass valves to ensure oil flow during media blockage. Variations exist for spin-on canister, cartridge, and remote filter systems, each requiring specific mounting and sealing features.