This paper reviews the history and mechanisms of zinc dialkyldithophosphate (ZDDP), a lubricant additive introduced in the late 1930s. ZDDP has been in continuous use for over 60 years and remains widely employed in engine oils, despite efforts to replace it. The review traces the development of ZDDP from its initial introduction to the present day, highlighting its success as an antiwear, antioxidant, and corrosion inhibitor. While significant progress has been made in understanding ZDDP's properties and morphology, there is still a lack of knowledge about the reaction pathways leading to film formation and the kinetics of film generation and removal. The paper focuses on research conducted in simple solutions, excluding interactions with other additives, to clearly illustrate ZDDP's mechanisms. The introduction of ZDDP is placed within the broader chronology of lubricant additive development, emphasizing the rapid growth in interest and research during the 1930s and 1940s.This paper reviews the history and mechanisms of zinc dialkyldithophosphate (ZDDP), a lubricant additive introduced in the late 1930s. ZDDP has been in continuous use for over 60 years and remains widely employed in engine oils, despite efforts to replace it. The review traces the development of ZDDP from its initial introduction to the present day, highlighting its success as an antiwear, antioxidant, and corrosion inhibitor. While significant progress has been made in understanding ZDDP's properties and morphology, there is still a lack of knowledge about the reaction pathways leading to film formation and the kinetics of film generation and removal. The paper focuses on research conducted in simple solutions, excluding interactions with other additives, to clearly illustrate ZDDP's mechanisms. The introduction of ZDDP is placed within the broader chronology of lubricant additive development, emphasizing the rapid growth in interest and research during the 1930s and 1940s.