Method description:
The test involves measuring the flow time of a sample through a calibrated capillary. The kinematic viscosity is calculated by multiplying the measured flow time by the capillary constant.
Interpretation of results:
Viscosity is usually determined at 40 and 100 °C, from which the viscosity index – a parameter describing the temperature dependence of viscosity – can be determined. The WL is characteristic of different oil types. The oil base and the type of additives used are important.
A viscosity test informs the user whether the oil used is as required. An increase in viscosity can indicate contamination/mixing, ageing, evaporation of the oil, a decrease in viscosity on the other hand can indicate dilution/mixing, cracking or mechanical degradation (shear stress).
