Viskositetshalter

Viskositetshalter, or viscosity index improvers, are chemical additives used in lubricating oils to reduce the change in viscosity with temperature. Lubricating oils naturally become thinner at higher temperatures and thicker at lower temperatures. This variation in viscosity can negatively affect an engine's performance and protection. Viskositetshalter are polymers that, when cold, are coiled up and do not significantly thicken the oil. However, as the temperature rises, these polymers uncoil and expand, counteracting the oil's natural tendency to thin. This helps maintain a more stable viscosity across a wider temperature range.

The effectiveness of a viskositetshalter is measured by its impact on the viscosity index (VI). A higher VI indicates a smaller change in viscosity with temperature. These additives are crucial for modern engine oils, especially those designed for multi-grade operation, allowing them to provide adequate lubrication during both cold starts and high-temperature operation. Different types of polymers are used, including olefin copolymers, polymethacrylates, and styrenic copolymers, each offering different performance characteristics and solubility in various base oils. The selection of a viskositetshalter depends on the desired viscosity grade, operating conditions, and compatibility with other oil components.