If you have the viscosity in centiPoise, divide the centiPoise value by the oil's viscosity to get centiStokes. This calculator uses centiStokes (cSt), which are equivalent to mm^2/s. Higher quality oils tend to have higher viscosity indices, and while there are ranges in every category, a synthetic oil will tend to have a much higher viscosity index than its conventional counterpart. The viscosity index can be calculated using the following formula: where U is the oils kinematic viscosity at 40 ☌ (104 ☏), Y is the oils kinematic viscosity at 100 ☌ (212 ☏), and L and H are the viscosities at 40 ☌ for two hypothetical oils of VI 0 and 100 respectively, having the same viscosity at 100 ☌ as the oil whose VI we are trying to determine. If you know the viscosity of your oil at 40✬ and 100✬ (100✯ and 212✯) you can easily calculate its Viscosity Index. Oil needs to flow when cold, but not get too thin and runny when it's warm. That is, oil with a high VI will retain their viscosity over a wider temperature range and work as designed in both hot and cold environments.Ī higher VI is important when your machine will experience a big change in operating temperatures. The viscosity index is an important value, especially for lubricants. Are you ready for your Eureka moment Articles. Roam the wiki and dive into a world of fascinating measurement methods and analytical principles. The higher the viscosity index, the lower the change in viscosity. The dynamic viscosity is the essential value for evaluating the lubricating behavior. Anton Paar Wiki is a living, growing scientific platform dedicated to highlighting the science behind your measurement solution. The degree to which the viscosity decreases determines the Viscosity Index (VI). The viscosity of an oil decreases as temperature increases. Viscosity range from 24 mPa.s to 320,000,000 mPa. Viscosity-temperature behavior of oils Compared to water, which has nearly the same flow behavior over a wide temperature range, oil changes its viscosity significantly with changing temperature. Viscosity Index and what you need to know Measure all liquid samples with the largest refractive index range of 1.30 to 1.72. To compare SUS (ASTM D88) with mm/s, an online calculator, such as the Anton Paar calculator for ASTM D88 / Saybolt universal viscosity can be used.

Anton paar viscosity index calculator