What is the importance of viscosity index improvers in lubricating oils used in industrial machinery?

Viscosity index (VI) improvers are additives used in lubricating oils to minimize the change in viscosity with temperature. Viscosity is a measure of a fluid's resistance to flow. Ideally, a lubricating oil should maintain a relatively constant viscosity over a wide range of operating temperatures to provide effective lubrication. Without VI improvers, lubricating oils tend to thin out significantly at high temperatures and thicken considerably at low temperatures. This can lead to inadequate lubrication at high temp....