Permanent Viscosity Loss of Viscosity Modifiers in Laboratory Bench Shear Tests

摘要

The extent to which multigrade engine oil viscosity degrades in laboratory bench tests is governed, in large part, by the response of polymer chemistry and architecture to the complicated stresses and flow geometries of the tests themselves. The process for establishing a more severe bench test to simulate greater viscosity loss under real driving conditions should include test oils intentionally formulated with a wide range of VM chemistries and evaluated in the field as well as in the laboratory. Choosing a more severe bench test without knowledge of the VMs in field reference oils can unnecessarily advantage or disadvantage some commercially important and valuable polymer chemistries.