ASTM D972 Evaporation Loss of Lubricating Grease and Oils
This method determines loss in mass of a grease or oil by passing heated air over the weighed sample for a fixed time (typically 22 hours). Because the air is heated by passing through a fixed length of tubing immersed in the same oil bath as the test cell, the actual temperature which the sample is subject to is less than the test temperature. The differential is significant (8, 10, 12°F or more) depending on test temperature. The highest test temperature is limited by the use of an oil bath (typically 300°F).