Viscosity measures a fluid’s resistance to flow, an important property of lubricating oils, the viscosity of oil changes with temperature, which can cause engine and machinery problems. Viscosity improvers (VIIs) are added to lubricating oil to improve its viscosity index (VI). This means that it maintains a more consistent viscosity over a wide range of temperatures, thus providing better protection and performance for the machinery.
How viscosity index improvers work:
Viscosity index improvers are typically made of polymers, such as polyisobutylene and polymethacrylate. These polymers are long-chain molecules that are designed to reduce the rate of change of viscosity with temperature. When added to lubricating oil, the polymers form a network structure that helps to stabilize the oil’s viscosity over a wide range of temperatures.
The rate of change of viscosity with temperature determines the VI of oil. The higher the VI, the more consistent the oil’s viscosity will be over a wide range of temperatures.
Benefits of viscosity index improvers:
Improved engine protection:
VIIs can help to maintain a more consistent viscosity of lubricating oil at low and high temperatures, which can help to reduce wear and extend the life of engines and machinery.
Reduced fuel consumption:
VIIs can help to reduce friction between metal surfaces, which can help to increase fuel efficiency and reduce emissions.
Improved cold weather performance:
VIIs can help to keep lubricating oil in a liquid state at low temperatures, which can help to reduce start-up wear and improve cold weather performance.
Better high-temperature performance:
VIIs can help to maintain the viscosity of lubricating oil at high temperatures, which can help to reduce thermal breakdown and improve high-temperature performance.
It’s important to note that VIIs are not a substitute for using lubricating oil with the correct viscosity grade for a specific application. The VI of the oil should match the operating conditions of the machinery.
Conclusion:
Viscosity index improvers (VIIs) are added to lubricating oil to improve its viscosity index (VI). This means that it maintains a more consistent viscosity over a wide range of temperatures, thus providing better protection and performance for the machinery. VIIs are typically made of polymers, such as polyisobutylene and polymethacrylate, and they have several benefits, such as improved engine protection, reduced fuel consumption, improved cold weather performance, and better high-temperature performance. However, it’s important to use lubricating oil with the correct viscosity grade for a specific application.
