First the viscosity at 100°C is calculated using the
viscosity at 40°C and the Viscosity Index. Calculation
according ISO 2909 / ASTM D2270-226. Then the viscosity at
temperature T is calculated with Ubbelohde-Walther equation
according ASTM-D341. A high VI-value indicates smaller viscosity changes with
temperature. The VI of conventional mineral oils roughly
ranges between 0 and 100, for modified mineral oils between
125 and 150, for synthetic esters between 140 and 160 and
for silicone oils up to 200. |