Viscosity Stability of Polymer-Thickened Oils 700053
A continuous, high speed road test has been found to accurately assess the shear stability of motor oils under all types of engine operation. It has also been demonstrated that a methacrylate polymer of sufficiently low molecular weight is completely shear stable under shearing conditions of the high speed road test. A road shear stability survey of commercial multi-graded oils has shown that some oils fail to produce the expected viscosity decrease due to oil oxidation. Preliminary road tests in diesel engines have shown the shear stability losses in polymer-thickened oils similar to those produced in the gasoline engines.
Shear stability studies in automatic transmission fluids by both bench and field tests have shown that this application is substantially more severe than the engine in shearing polymeric V.I. improvers.