AbstractIn combination with the use of SEP‐PAK cartridges and computerized difference infrared spectroscopic technique, a simple novel method for analyzing lubricating oil additives was developed. The present method involves solvent extraction and the use of SEP‐PAK C18for separating polar additives from residual base oil, followed by the use of SEP‐PAK Silica for further elution. With the aid of infrared data station, components of the polar additives were identified. The present method is definitely much more rapid and efficient than the conventional column separation method, and the separation efficiency of this simple method is comparable to that of using flash chromatographic tech