 While descending, the plane's airspeed rises, substantially increasing the rate of air-cooling the engine.These factors may cause the cylinder head to crack; but the adoption of oil-cooled cylinder heads significantly reduces or cancels the problem as the heads are now "oil-warmed".In the 1980s, Suzuki used the "SACS" oil-cooling system on the GSX-R sportbikes, but later switched to water-cooling.