Viscosity Effects on Engine Wear Under High-Temperature, High-Speed Conditions

Abstract

<div class="htmlview paragraph">Four multigrade engine oils, containing the same base oil plus SE additive package but VI improvers of differing shear stability, were evaluated in 80 000 km of high-speed, high-temperature vehicle service.</div> <div class="htmlview paragraph">Bearing, piston ring and valve guide wear, as well as oil consumption, oil filter plugging and engine cleanliness were all worse for the engines operated on the low-shear stability oils. The wear differences were traced to differences in high-shear-rate viscosity, while the cleanliness, filter plugging and oil consumption differences occurred because of excessive wear or polymer shear degradation.</div> <div class="htmlview paragraph">These results suggest that engine oil viscosity should be specified under high-shear-rate conditions.</div>