The Relationship of Journal Bearing Wear to Multigrade Engine Oil Viscometric Properties

A high speed road test procedure was developed to demonstrate performance of multigrade engine oils in journal bearing wear protection. High shear viscosities of test oils were approximated through use of a pump loop. A reasonable first approximation of critical viscosity for bearing failure is estimated by measurements at 149°C and about 5Xl0₅ sec _-1 with the pass/fail limit being about 3.5 cSt.