Yamaha Superior Valve Oils are based on an advanced synthetic formula that is produced using a consistent molecule size. Standard valve oils contain mineral oil, which is made up of molecules varying in size. The varied molecule make-up of mineral oil allows the oil to evaporate at an uneven rate, leaving high viscosity particles behind. The even molecules found in the new Yamaha Superior Valve Oil synthetic formula allow the oil to evaporate smoothly, guaranteeing a longer life and extremely responsive action. Yamaha Superior Valve Oils contain a unique anti-corrosive agent, which greatly outperforms the competition. The new additive prevents all types of corrosion and will protect valves and valve casings in nearly every playing environment.