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A field test method to quantitatively determine oxidation stability of gasoline engine oil

As oxidation stability of engine oil was hard to evaluate in field, this paper tried to propose a field test method to determine the oxidation onset temperature (OOT) of gasoline engine oil. A theoretical model of grey average value of oil spot image and OOT was established by using spot test method, image processing, and Pressure Differential Scanning Calorimetery method. The oil sample unknown OOT was taken to spot test and image processing in field to obtain the grey average value. The OOT can be calculated by bringing the grey average value to the established theoretical model. This approach was successfully used for OOT determination of 4 different kinds of engine oils with good accuracy and precision. The absolute error of mineral oils was less than 4.52°C, and synthetic oils were less than 1.2°C. This convenient, low‐cost, and reliable method can achieve OOT of engine oil in field determination and provide reference for engine oil drain interval evaluation.