The thermal requirements on motor oils in particular have risen considerably over the last few years. This consequently means that the testing of these motor oils and lubricants has nowadays become more important for reasons of quality control and operating safety. Evaporation losses at high temperatures generally lead to an increase in the oil consumption and additionally cause a detrimental change in the lubrication properties of the oils.
The test method is standardized in DIN 51581, CEC L-40-A-93 and ASTM D5800. The oil sample is heated in the evaporation crucible, and subsequently retained at the testing temperature for exactly 60 minutes. Whilst the testing temperatures can generally be as high as 350癈, motor oils are usually tested at