Millions and millions of micron-sized specks collect in your engine oil as it flows . . . and the hard-working filter catches and holds them. Until it’s so clogged with dirt it can’t hold any more. When this happens, the oil-supply by-passes the filter and continues circulating unfiltered, through your engine . . . getting dirtier and more dangerous with every revolution. On its way through the engine, oil collects countless specks of abrasive dirt and carries them through to the sump. The filter removes them, to prevent the excessive wear they can cause upon contact surfaces. If the filter is clogged and cannot hold any more dirt, these dangerous particles continue to circulate with the oil, shortening the life of pistons, bores and bearings.