AMSOIL INC. has determined that the reduced wear and extended drain intervals achievable with phosphorous levels higher than the API limit of .10% are real benefits for the consumer, and pose no risk to catalytic converters. AMSOIL motor oils, except for the API licensed XL-7500 5W-20, 5W-30, 10W-30, 10W-40 and 15W-40 PCO viscosity grades, all have greater than .10% phosphorous levels, and therefore, cannot be API licensed.