ABSTRACT
The very nature of lubricant service means that lubricants deteriorate during their service use. It is normal for lubricants to degrade by partial evaporation, oxidation, and contamination. The purpose of lubricant formulation for a defined application is to control the deterioration of that lubricant in a planned manner over an established period of time, work, distance, or operation. The deterioration of a lubricant can either be planned and controlled by various means or be uncontrolled. Modern practice is strongly directed to the former.
