Oil control ring definition
A piston ring designed to scrape oil from the cylinder wall , the ring is of such a design as to allow the oil to pass through the ring and then through holes or slots in the groove . In this way the oil lubricates the cylinder walls and is returned to the pan rather than getting into the combustion chamber where it might foul the spark plugs and create carbon on the head of the cylinder . There are many shapes and special designs used on oil control rings. Often it is the third or fourth ring from the top.