For your consideration is this RPM Aviation Oil & Chevron Aviation Gas, Standard of California RPM aircraft lubrication guide printed in 1947 and copy-righted by the California Research Corporation. This book gives extensive information on lubrication services for over forty different aircraft from various manufactures. Large, full page diagrams are shown with the diagram of the aircraft in the center, the manufacturer in the bottom left and the model/type in the bottom right hand corner. Some of the information included is recommended lubricants, service interval times, fuel and oil recommendations, reservoir capacities, tire information and other detailed instructions. Some of the aircraft included are Waco Model UPF-7, Taylorcraft Model D, Stinson Voyager 150, Stinson Models HW-75,10,10A, Ryan Model ST-3KR, Porterfield Collegiate, Piper Model J4, North American Navion, Monocoupe Model 90, 90A, 90AF and many more. The portfolio is set on a metal ring holder. It shows fair to good condition with foxing and staining present on most pages and tears present from its age and use over the years. Major signs of damage not noted on the piece. It measures 13 1/8" L x 18 5/8" W x 3/8" D and weighs 2 pounds and 6 ounces.