Base Oil Viscosity Index Calculator

Formula

The formula to calculate the Viscosity Index (VI) is:

\[ VI = \left(\frac{L - U}{L - H}\right) \times 100 \]

Where:

\(VI\) is the Viscosity Index
\(L\) is the viscosity of the oil at 40°C
\(U\) is the viscosity of the oil at 100°C
\(H\) is the viscosity of a reference oil at 100°C

What is Base Oil Viscosity Index?

The Base Oil Viscosity Index is a measure used to indicate the change in viscosity of lubricating oil with changes in temperature. It is a dimensionless number that represents how much the oil’s viscosity changes as temperature changes. A higher viscosity index indicates a smaller decrease in viscosity with increasing temperature, meaning the oil will maintain its lubricating properties better under high temperatures. This is crucial in applications like engines and machinery where temperature conditions can vary greatly.

Example Calculation

Let's assume the following values:

Viscosity at 40°C (L) = 100
Viscosity at 100°C (U) = 20
Viscosity of Reference Oil at 100°C (H) = 10

Using the formula to calculate the Viscosity Index (VI):

\[ VI = \left(\frac{L - U}{L - H}\right) \times 100 = \left(\frac{100 - 20}{100 - 10}\right) \times 100 ≈ 88.89 \]

The Viscosity Index (VI) is approximately 88.89.