Mercury oil change kits contain industry-leading Mercury 25W-40 Marine Engine Oil. Over five years of engineering and development went into the exclusive Flagship Protection formula which features a high-tech, advanced set of anti-wear additives that provide up to 35% better camshaft wear protection and the highest levels of corrosion and oxidation protection. Designed to maintain engine reliability and performance, Mercury 25W-40 Marine Engine Oil has been proven to hold its viscosity ratings longer in industry wear testing than other oils on the market. Mercury Oil, combined with a genuine Mercury Oil Filter team up to provide the #1 protection on the water.