A New Technique for Simple and Rapid Discrimination of the Stages of Used Oil Degradation

A simple colorimetric method for determination of base number (BN) [1] in used engine oil with test strips was developed. As oil ages with use, the alkalinity decreases. Thus titration methods are commonly employed for the determination of BN. In this research, test strips were constructed using a pH indicator impregnated in a membrane filter. The color of the test strip changed from pink to green with sufficient alkaline in the engine oil. When the membranes are acid pretreated, this method can discriminate among different degrees of BN loss. Thus the new technique has been successful applied to judge the degradation stage of engine oil.