STP1068

    Change of High-Shear-Rate Viscosity of Engine Oils During Use: A Review

    Published: Jan 1989


      Format Pages Price  
    PDF (240K) 14 $25   ADD TO CART
    Complete Source PDF (2.0M) 14 $55   ADD TO CART


    Abstract

    It has long been known that the kinematic viscosities of multigrade engine oils change with use, the typical pattern being an initial decrease followed by a gradual increase. Recent work has shown that the patterns of change of the high-temperature, high-shear (HTHS) viscosity are different than those of the kinematic viscosity. These results, coupled with recent bearing oil film thickness results, suggest that kinematic viscosity changes are less significant in the operation of the bearings of engines than has been assumed. The pattern of HTHS viscosity change has been found to depend on both viscosity index (VI) improver type and engine test. Oil-thickening effects tend to be more prominent in the HTHS viscosity patterns than in the kinematic viscosity patterns.

    Keywords:

    engine oils, polymers, shear stability, shearing, VI improvers, viscometer, viscosity


    Author Information:

    Alexander, DL
    Technologist, Texaco Research Center, Beacon, NY


    Paper ID: STP23003S

    Committee/Subcommittee: D02.07

    DOI: 10.1520/STP23003S


    CrossRef ASTM International is a member of CrossRef.