Viscosity measurement at 40 degrees gives a picture of the oil's properties at moderate temperatures, such as in hydraulic systems and gearboxes. It is a standard temperature that provides comparability and predictability.
By passing the oil through a calibrated capillary system, we measure the time it takes for a certain amount of oil to pass – this gives the viscosity value in cSt.
The result shows whether the oil has retained its properties or whether it has been affected by dilution, oxidation or aging.