VISCOSITY INDEX IMPROVER (VI IMPROVER) Viscosity Index Improvers are special additives designed to reduce the viscosity dependence of oils on temperature. These additives help maintain consistent oil performance across a wide range of operating temperatures, ensuring proper lubrication and protection for engines and machinery. The viscosity index (VI) is a measure of how much the viscosity of an oil changes with temperature. A higher VI indicates that the oil's viscosity changes less with temperature, which is desirable for maintaining consistent performance. VI Improvers work by expanding at higher temperatures, which helps maintain the oil's viscosity. At lower temperatures, they contract, allowing the oil to flow more easily. This property makes them essential for multi-grade oils that need to perform well in both cold starts and high-temperature operation. These additives are commonly used in engine oils, transmission fluids, and hydraulic fluids to ensure optimal performance across different operating conditions.