By Jim Fitch
Practicing Oil Analysis Magazine
When an oil’s viscosity makes a significant change it is meaningful. The majority of the characteristics associated with wrong, contaminated or degraded lubricants will cause a change in viscosity. Restated, when trending the viscosity of a used oil and no reportable change occurs, one can conclude that many of the things that could be happening to the oil are not yet occurring. These include oxidation, shear thinning, thermal degradation and many other common condemning conditions.