Oil ring

An oil ring is one component that fits into the ring groove on a piston. Works to scrape off excess lubricant adhering to the cylinder wall so that the oil does not enter the combustion chamber.
Generally, the outer circumference of the ring is grooved, and the groove has evenly spaced oil return holes.
The oil ring groove is also perforated, so some of the scraped oil is returned to the crankcase through the oil holes in the ring and piston.

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