An oil filter for an engine is in the form of a reservoir mounted in an oil pan having a closed interior volume and an open top edge spaced from an adjoining oil pan sidewall and positioned to receive oil with entrained debris as the oil flows by gravity after being centrifugally flung radially outward from the moving engine components. The debris separates from the oil in the reservoir, with clean oil overflowing the top edge of the wall for recirculation in the engine.
