What happens to hydraulic fluid viscosity with a temperature increase?

Hydraulic fluid viscosity generally decreases with an increase in temperature. This behavior is due to the physical properties of fluids and how temperature influences their molecular activity. As the temperature rises, the molecules in the hydraulic fluid gain more kinetic energy and move more freely, leading to a reduction in the internal friction within the fluid. Consequently, this lower viscosity allows the fluid to flow more easily through components of the hydraulic system, reducing resistance and improving performance.

This principle is essential in hydraulic systems because, as the operating temperature varies during use, it impacts the system's efficiency and responsiveness. Understanding this behavior helps technicians and engineers select the appropriate hydraulic fluids for specific applications and ensures the reliable operation of hydraulic equipment.