A method is presented for obtaining vapor pressures over the temperature range of interest in engine lubrication (300–500 F). The determination is based on the saturation efficiency of an air stream and the relationship between vapor pressure and evaporation loss. All data required are readily obtained from the ASTM Evaporation Test Method D 972-56 which is already used in connection with the evaporation loss specification of turbo oils. In addition to vapor pressure, the method is also used to estimate the flash point of these same lubricants.Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE Lubrication Conference held in Atlantic City, New Jersey, October 8–10, 1968.