Six fully formulated fluids spanning two viscosity grades and three viscosity index levels were evaluated in a laboratory dynamometer and two excavators. In the excavator test, combining low-viscosity with high-viscosity index increased productivity in river stone truck loading operations. This low-viscosity/high-viscosity index combination increased leakage flow rates in dynamometer testing. Hydraulic circuit analysis is used to explain the differences in the dynamometer and excavator responses to fluid properties. These findings provide insight into how hydraulic fluid optimization can enhance machine productivity.

• Interesting differences between laboratory dynamometer and excavator field testing of fluids
• Three key fluid properties that affect hydraulic system performance
• Which fluid properties have the biggest effect on torque and flow losses in dynamometer testing
• Which fluid properties have the biggest effect on cycle times and payload in excavator testing
• Why improved productivity, rather than reduced fuel consumption, drives better fuel economy in excavator testing