The viscosity index describes how much the viscosity changes with temperature. A high viscosity index means that the oil maintains a uniform viscosity at both low and high temperatures, which is desirable in many machine systems.
The index is calculated on the basis of viscosity measurements at 40 ℃ and 100 ℃. The less the viscosity varies, the higher the index.
The customer receives information about the stability of the oil at temperature fluctuations — an important decision-making basis for equipment subjected to varying operating conditions.