THE MAJOR FUNCTION OF LUBRICATING OILS is the reduction of jxiction and wear by the separation of surfaces, metaUic or plastic, which are moving with respect to each other. The oils also act as carriers for many special chemicals such as corrosion inhibitors, anti-wear agents, load-carrying friction modifiers, and foam suppressors. Performance requirements can also include cooling, the dispersion and neutralization of combustion products from fuels, and the transport of contaminants to a filter. The high-quality and improved properties of present-day lubricants have enabled engineers to design machines with higher power-to-weight ratios that generally have higher stresses, loads, and operating temperatures than before. Thus, it has been possible to develop automobile engines, turbines, gear sets, etc., capable of higher speeds and higher specific power output per unit weight of machinery. In a very different field, lubricants with increased resistance to the effects of radiation have been developed for nuclear power stations.