you understand your engine's lubrication system, the more
you'll appreciate the vital role your oil filter plays. When
the engine is running, oil enters the oil pump through a screened
intake. The screened intake -- or oil pick-up -- is located
in the crankcase near the bottom surface of the oil pan. The
oil is drawn through the screen intake and forced by the oil
pump through the oil filter.
the main gallery is also fed through vertical passages to
the crankshaft main bearings and through the crankshaft to
the rod bearings. Oil thrown from the crankshaft, or sprayed
from the connecting rods, lubricates the pistons and cylinder
In a typical
full-flow type oil filter, the oil flows into an inlet passage
and then through the filtering element. After flowing through
the filter element, the filtered or "clean" oil
passes directly to the main oil gallery. In a partial-flow
type filter, the oil returns directly to the oil pan.
the main gallery lubricates the camshaft and the camshaft
bearings (and feeds hydraulic valve lifters if used in the
engine). On non-overhead cam engines, oil is metered through
the valve lifter to a hollow push rod that carries oil for
the lubrication of the push rod pivot point, rocker arm pivots
and valve guide.