Engine lubrication is supplied by a gerotor type oil pump assembly (10). The oil pump assembly (10) is mounted on the front of the engine block and driven directly by the crankshaft sprocket. The oil pump gears rotate and draw oil from the oil pan sump through a pick-up screen and pipe (9). The oil is pressurized as it passes through the oil pump and is sent through the engine block lower oil gallery. Contained within the oil pump assembly (10) is a pressure relief valve that maintains oil pressure within a specified range.

Pressurized oil is directed through the engine block oil gallery (4) to the full flow oil filter (8) where harmful contaminants are removed. A bypass valve is incorporated into the oil pan at the oil filter, which permits oil flow in the event the filter becomes restricted. A second valve, the active fuel management oil pressure relief valve (7) is incorporated into the oil pan. The active fuel management oil pressure relief valve (7) limits oil pressure directed to the upper oil galleries (4) and valve lifter oil manifold assembly (1) to 379-517 kPa (55-75 psi) maximum. When main oil pressure exceeds 379 kPa (55 psi), the oil pressure relief valve exhausts excess oil to the sump.

Oil is then directed from the filter to the upper main oil galleries (4). Oil from the left upper oil gallery is directed to the crankshaft bearings (11) and camshaft bearings (12). Oil that has entered both the upper main oil galleries also pressurizes the valve lifter assemblies (5 and 6) and is then pumped through the pushrods to lubricate the valve rocker arms and valve stems. Oil returning to the pan is directed by the crankshaft oil deflector. The oil pressure sensor (2) and valve lifter oil filter (3) a is located at the top rear of the engine.

With active fuel management activated, the ECM commands the 4 solenoids to open, directing oil through the engine block oil galleries to the intake and exhaust valve lifters for cylinders 1, 4, 6, and 7.