AMSOIL: Normal Service – Up to 25,000 miles (40,200 km), 700 hours of operation or one year, whichever comes first, in personal vehicles not operating under severe service. Severe Service – Up to 15,000 miles (24,140 km), 700 hours of operation or one year, whichever comes first. AMSOIL uses naturally shear-resistant base oils combined with top-tier, shear-stable viscosity improvers. AMSOIL synthetic motor oil withstands extreme heat and shearing forces, exceeding industry standards and outperforming competing brands. In fact, it fights viscosity breakdown 46 percent better than Mobil 1.