What is Viscosity and what might be happening when it increases?
Viscosity is a measurement of a fluid’s resistance to flow at temperature. In other words, viscosity is the film strength or thickness of the oil. It is considered the most important fluid property test for oils because a change in viscosity can be an indication of many problems such as oxidation, nitration, water contamination, soot contamination (engines), shearing (when molecules are split), coolant contamination or mixing lubes with different viscosities.