Oils used in aviation engines have a specific grading system exclusive to aviation lubricants. Aviation Grade 65 oils are equivalent in viscosity to SAE 30 oils (i.e. 11.1 cSt @ 100°C). The SAE standard is applied to lubricants of various applications and stands for the Society of Automotive Engineers. Essentially, the SAE standard is derived from a specific testing method for lubricants - this designation isn't to say these oils are for use in automotive engines.
Grade 65, SAE 30 Aviation oil is almost exclusively used for the break-in of most four-stroke cycle certified aviation piston engines.