The component with the lowest price in the OIL FILTER / OIL PUMP schematic is the Bolt,hex 6x32.
Some items from this specific schematic: Body,comp.,pump, Gasket,oil Pump (nas), Nut, Lock, 16m/m, Bolt,hex,6x32.
With a quantity of three pieces, the Bolt,hex 6x32 is the most used part in the OIL FILTER / OIL PUMP diagram.