GM Service Manual Online
For 1990-2009 cars only

The oil pump is of a trochoid type, and is mounted under the crankshaft. Oil is drawn up through the oil pump strainer and passed through the pump to the oil filter. The filtered oil flows into 2 paths in the cylinder block. In one path , the oil reaches the crankshaft journal bearings. Oil from the crankshaft journal bearings is supplied to the connecting rod bearings by means of intersecting passages drilled in the crankshaft, and then injected from the big end of the connecting rod to lubricate the piston, rings, and cylinder wall.

In other paths oil goes up to the cylinder head and lubricates valves and camshafts after passing through he internal oilway of camshafts.

An oil relief valve is provided on the oil pump. This valve starts relieving oil pressure when the pressure exceeds about 420 kPa (59.7 psi).