Lubricants commonly employed in aviation engine oils generally use a SAE "Aviation" Grading system for recommending oil viscosity for a particular engine. In the small sport aviation engines, light engines and ultra-light engines they have always recommended automotive passenger car and motorcycle engine oils for their application. Now that there is engine oils that are made just for these types of engines they still carry the SAE "Automotive" Grading for the oil itself. In this case it is aviation engine oils with a Viscosity SAE Grade of 10w-40.
