Ultra-Pure Professional Valve Oil is known for its fast and smooth action. It is synthetic, non-toxic, odorless and very long-lasting. It is harmless to all metals, including brass, aluminum, stainless steel, monel, nickel, silver, copper, gold, solder, lacquer finish, etc. In over fifteen years of continuous use on brass instruments of all kinds, makes and models, no one has reported any kind of corrosion, build-up or discoloration problems. -the manufacturer