Documented articles have been published on the very early development of aircraft piston engine oils covering the transition from castor oil to various types of nonadditive, mineral-base lubricants. This documentation covers the history and development of these lubricants up to and including the World War II era and into the late 1940's. A considerable amount of research and development of greatly improved lubricants has occurred since that time. Although numerous articles have dealt with certain phases of this development, no attempt has been made to organize this period into a chronological and thorough historical perspective. This paper attempts to fill the gap in the development of aircraft piston engine lubricants during the past 40 years.