The Non-Newtonian Characteristics of Lubricating Oils

Interest is growing concerning the influence of polymeric additives upon the viscosity of mineral oils at extremes of temperature, pressure, and shear. In this paper the author discusses the viscometry of mineral oils and mineral oil-polymer blends at moderate temperatures and high shear and at low temperatures and low shear. The non-Newtonian influences of two common polymeric additives, polyalkylmethacrylate and polyisobutylene, are shown to vary considerably at low temperatures in their effects on a common base oil. Shear dependence of polymer-containing oils at high shear rates is experimentally indicated to reduce the viscosity of the blend to approximately that of the base oil. Conclusions of practical interest are drawn from the experimental results. Contributed by the ASLE Technical Committee on Lubrication Fundamentals and presented at the Annual Meeting of the American Society of Lubrication Engineers held in Detroit, Mich., April, 1957.