Signature Series A. New Level of Motor Oil Technology Engineered for enthusiasts seeking maximum protection and performance. Precision-formulated with cutting-edge technology and a longstanding devotion to making the world’s best motor oil. The result: engine protection that blows the doors off the highest industry standards. 75% more engine protection against horsepower loss and wear. 50% more cleaning power vs. AMSOIL OE Motor Oil Protects turbochargers 72% better than required by the GM dexos1 Gen 2 specification. 28% more acid-neutralizing power than Mobil 1. Trusted by professional engine builders Guaranteed protection for up to 25,000 miles or 1 year Fights Engine Wear 75 percent more engine protection against horsepower loss and wear1 than required by the industry standard, extending the life of vital components like pistons and cams. Develops a strong fluid film that keeps metal surfaces separated. Robust anti-wear additives further reduce wear in metal-to-metal contact regions for maximum engine life. Signature Series Provides Powerful Protection AMSOIL provides powerful protection. How good is it? An independent lab compared AMSOIL synthetic motor oil head-to-head against a leading competitor in a 100,000-mile test. AMSOIL provided far stronger wear protection and kept bearings looking like new. Signature Series Resists Viscosity Increase Signature Series is barely challenged by the industry-standard testing, demonstrating only a 0.1% viscosity increase. Even when the test length is doubled, AMSOIL delivered twice the viscosity control required by the standard. Signature Series Helps Keep Engines Cleaner Fortified with a heavy treatment of detergent additives, providing 28% more acid-neutralizing power than Mobil 1* and helping engines stay cleaner, longer. 50% more detergents to help keep oil passages clean and promote oil circulation. Controls heat and minimizes performance-robbing deposits. Stronger thermal long service life that resists breakdown and keeps pistons clean. Provides 90% better protection against sludge.