Piston Ring Set MGB 1963-1965. These ring sets contain compression rings which are manufactured to precision specifications from high grade castings. The rings are beveled on the inside top, which gives a torsional twist characteristic or relieved on the lower ridge for oil scraping characteristics. This second ring type is generally used in the second groove. Oil rings are of either circumferential design or Grant’s patented channel oil ring, both of which provide quick seating, positive oil control and long life. All Grant rings are parkerized to protect the ring, improve lubrication and to initiate a quicker seal.