Following successful laboratory validation of the filtration medium, a skid incorporating the VRF filter modules and the associated control system was tested on two operating turbines. The treatment of the turbine lubrication systems entailed installation of the skid in a kidney-loop mode, taking the fluid from one end of the reservoir and returning it to the opposite end continuously. Both trials ran uninterrupted with minimal operator intervention and utilized one set of three VRF modules for each trial. The removal and retention of varnish material by the filtration medium was indicated by the staining of the medium by the varnish material.