An oil filter assembly is disclosed for a machine, such as an internal combustion engine, that has oil output and input ports. A mounting plate is fixed with an outer enclosure and is adapted for securing to the machine and conducting oil therefrom into a peripheral portion of the outer enclosure, and then returning oil from a central portion of the outer enclosure back to the machine. Oil may pass from the peripheral portion to the central portion through a primary filter having a first porosity. Oil may pass through a pressure-actuated valve fixed fluidly between the peripheral portion and central portion of the outer enclosure only when an oil pressure differential exceeds a predetermined threshold pressure. A secondary filter has a second porosity greater than the first porosity, and is fixed fluidly between the pressure-actuated valve and the central portion of the outer enclosure.
