from the amsoil page:
SERVICE LIFE
AMSOIL Synthetic 10W-30 Motor Oil is recommended for extended drain intervals in unmodified(1), mechanically sound(2) gasoline fueled vehicles as follows:
• Normal Service(3) – Up to 25,000 miles or one year, whichever comes first.
• Severe Service(4) – Up to 15,000 miles or one year, whichever comes first.
• Replace AMSOIL Ea full-flow oil filter at the time of oil change up to 25,000 miles or one year service life, whichever comes first (other brands at standard OEM* intervals).
• In all other applications, extend the oil change interval according to
oil analysis or follow the OEM* drain interval.
*OEM – Original Equipment Manufacturer
(1) Engines operating under modified conditions are excluded from extended drain recommendations. Examples include the use of performance computer chips; non-OEM approved exhaust, fuel or air induction systems; and the use of fuels other than those recommended for normal operation by the manufacturers.
(2) Engines are in good working condition and within the factory design settings. Mechanically sound engines, for example, do not leak oil or consume excessive amounts, are not worn out, do not overheat, do not have internal or external anti-freeze leaks and have properly working emission control systems. AMSOIL recommends repairing malfunctioning engines prior to the installation of AMSOIL synthetic oils.
(3) Personal transportation vehicles frequently traveling greater than 10 miles (16 km) at a time and not operating under severe service.
(4) Turbo/supercharged vehicles, commercial or fleet vehicles, excessive engine idling, use of AMSOIL engine oil in vehicles with over 100,000 miles without prior regular use of AMSOIL engine oil, daily short trip driving (less than 10 miles), frequent towing, plowing, hauling or dusty-condition driving.
