Complex sentence: The standard certification for the C90 and O-200 specifies the use of aviation gasoline of a minimum 80/87 grade; both are eligible for operation on automobile gasoline on the basis of Supplemental Type Certificates.
Split into simpler sentences: The standard certification for the C90 and O-200 specifies Avgas 80/87 as the minimum fuel grade. Both are eligible for operation on automobile gasoline on the basis of Supplemental Type Certificates.