AMSOIL Signature Series Synthetic Motor Oil is guaranteed for extended drain intervals in unmodified1, mechanically sound2 gasoline-fueled vehicles as follows:

  1. Engines operating under modified conditions (non-stock) 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 manufacturer.
  2. Mechanically sound engines are in good working condition and do not, for example, leak or consume excessive amounts of oil, are not worn out, do not overheat, do not leak antifreeze and have properly working emissions control systems. AMSOIL recommends repairing malfunctioning engines prior to the installation of AMSOIL synthetic oils.
  3. Personal vehicles frequently traveling greater than 10 miles (16 km) at a time and not operating under severe service.
  4. Turbo/supercharged engines, commercial or fleet vehicles, excessive idling, vehicles with more than 100,000 miles without prior continuous use of AMSOIL motor oil, daily short-trip driving less than 10 miles (16 km), frequent towing, plowing, hauling or dusty condition driving.

AMSOIL Ea® Full-Flow Oil Filters are designed for extended change intervals. They stop smaller particles, flow more oil and last longer than regular filters. For best performance, use AMSOIL Ea Oil Filters. While Signature Series' 12-month service life remains intact if a non-Ea Oil Filter is used, the filter must then be changed according to its manufacturer's recommendations.

It is normal for vehicles to use some oil between oil changes. Check your oil regularly to ensure your oil remains at a safe level.