On average, additives make up to 7% of a typical lubricant base. Commonly, they\nare blended with lube oils to enhance specific features thereby improving their qualities.\nUltimately, additives participate in the performance of car engine oils. Using an analytical\ntool, attenuated total reflectance fast transform infrared spectroscopy, various grades of car\nengine oils, at different mileages, were analyzed. Sulfate oxidation and wear were found to\ntrigger chemical processes which, in the long run, cause lubricant degradation while carbonyl\noxidation was observed to occur only at a slow rate. Based upon data obtained from infrared\nspectra and using a curve fitting technique, mathematical equations predicting the theoretical\nrates of chemical change due to the aforementioned processes were examined. Additive\ndepletions were found to obey exponential regression rather than polynomial. Moreover,\nbreakpoint (breakpoint is used here to denote the initiation of deterioration of additives) and\ncritical mileage (critical mileage defines the distance at which the lubricant is chemically\nunusable) of both samples were determined.
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