Multipurpose Tractor Hydraulic Fluids Field Test-Used-Oil Analysis and its Significance

A field test of one commercial oil and two self-formulated oils with two different viscosity grade was conducted on 31 tractors. The key properties for monitoring used-oil degradation are viscosity, IR spectrum, wear metals, water and silicon contents. TAN and insolubles did not change significantly during service. The models capable of characterizing used-oil properties are proposed. The warning limits are established and the relationships between bench tests and field performance are also discussed.