Engine Oil Viscometry and Viscometers – Fact and Fallacy

Viscosity has always been a critical property of lubricants. It is the source of the hydrodynamic lubrication that separates lubricated surfaces moving past one another under pressure and thus is a major factor in reducing wear. On the other hand, viscosity is also a form of friction – viscous friction – and, as it absorbs energy, viscosity reduces the efficiency of the engine even as it protects it.