The ongoing trend for using low viscosity lubricants, with the aim of improving the efficiency of mechanical systems, means that machine components are operated for long periods under thin film, boundary and mixed lubrication conditions. This increases the risk of surface damage such as wear, scuffing and pitting. In order to provide adequate surface protection, the role of lubricant additive has become increasingly important. Among such additive, polymeric additives have been widely used, especially to control lubricant viscosity. Recently, these are used to form adsorption film to reduce surface damage under boundary and mixed lubrication and to reduce friction. This paper reviews the effect of polymeric additives on lubricant performance and outlines the research and the mechanisms by which they are currently believed to function.
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