The cheapest rings are gray iron rings that are not coated. these rings were the standard low-cost chaff installed by OEMs in the day, and are usually found in bottom-of-the-line rebuilder's kits. Rings often receive a surface treatment on the face surface to enhance the friction, wear, or oil retention capabilities of the base ring. The most common surface coating in high-performance usage is a moly coating, which is exceptional on all three counts. Gray iron rings are available with a moly coating, which significantly improves the ring in reducing friction and wear. These lower cost moly rings offer all of the positive attributes of the moly surface material, but gray iron rings are no more resistant to stress than plain iron rings. In a stock or mild performance application, they work quite well, and are a far better choice than a plain iron ring and greatly reduce bore wear. Ductile iron rings are almost always moly coated, and the ductile iron moly ring has become the standard of the performance industry. Chrome-faced rings were once a popular choice, as chrome has excellent frictional and wear characteristics. Chrome is more wear resistant and durable than moly, however, it is a hard material, making for difficult break-in and seating. For these reasons, chrome rings have fallen out of favor.

Ring Widths
Back in the era of the musclecar, the industry standard in ring widths consisted of a pair of 5/64-inch compression rings and a 3/16-inch oil ring. Ring width has a direct bearing on ring friction. over time, racers adopted narrower 1/16-inch compression rings, finding a substantial and worthwhile reduction in ring friction and the expected increase in power. Narrower rings have less surface area at the face riding on the cylinder wall, so the lower friction was an obvious benefit. It was believed that a reduction in ring-face surface area also meant shorter ring life. OEMs stuck with cheap cast-iron 5/64-inch rings for decades, until finally following the lead of the racing community to narrower rings. Improvements in lubrication and, more significantly, materials proved far more relevant to ring life than the width of the ring. These days, modern engines are commonly fitted with 1/16-inch or narrower moly rings, and engine life is actually far better than it was back in the day. Chrysler made the switch in its V-8 engine lineup with the introduction of the Magnum engine series in the early '90s.

In addition to the friction reduction, narrower rings are proportionally lighter, providing an improvement in high-rpm performance. Compression rings react to changes in combustion pressures, sealing to the ring land of the piston and cylinder wall. At high rpm, a lighter ring has the advantage of less inertia and is better able to achieve a positive seal. Racers now commonly use a ring package, including a top ring measuring .043-inch, taking the next step in reducing friction and ring weight. For street, bracket, and sportsman racing, and/or street/strip use, look no further than the 1/16-, 1/16-, 3/16-inch ring package. This ring arrangement will achieve a substantial gain in reduced friction and sealing, without the high cost of more exotic packages. For true professional racing, the thinner ring packs using .043-inch first and/or second compression rings and 3mm oil rings are becoming the norm.