RULER(TM) and used engine oil analysis programs

This paper presented the results of research to evaluate the Remaining Useful Life Evaluation Routine (RULER(TM)) for engine oils. The RULER(TM) studied in this paper is based on a voltammetric method. The remaining useful life (RUL) is the length of engine/equipment operating time from the time a lubricant is sampled until large changes in the lubricant properties occur at which point the lubricant cannot function properly. The ability to predict the RUL of lubricants would broaden the information on the oil condition, allowing operators to reschedule oil changes and potentially provide cost benefits. A series of samples from different equipment types/manufacturers, both engine and field trials, were analyzed using the instrument. The antioxidant capacity of each used engine oil was determined and compared to the new oil. The results showed that the antioxidant capacity depleted with time, bur that the rate of depletion varied depending on operating conditions. The RULER(TM) results were compared to other standard oxidation and physical tests, differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), total acid number (TAN), total base number (TEN) and viscosity to determine any correlation between the techniques. It was also found that different oils gave characteristic RULER(TM) traces, which could be used to identify erroneous top-ups, or mislabeling of samples.