clean oil is the lifeblood of your engine. You may think that your oil filter is not that important, but this small, inexpensive part is far from trivial. It plays a vital role in protecting your engine from premature wear by cleaning the oil as it passes through the filter element. Each moving part in the engine requires uncontaminated oil for proper lubrication and long life.
A good filter has a strong canister that can withstand high oil pressure when the engine is cold, an anti-drainback valve that keeps dirty oil from returning to the engine without creating too much backpressure, a pressure-relief valve that doesn稚 leak under low pressure, and a filtering element that can withstand boiling-hot oil without falling apart. The filter element also has to be able to trap small particles without restricting flow, and do it for thousands of miles. Doesn稚 sound so trivial now, does it?
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Oil Filter Comparison: Filter Fodder - Four Wheeler Magazine