3. Base Oil Finishing After extraction and dewaxing, the base oil is still not ready to produce lubricating oils. Lubricating oils are required to employ finishing step, such as clay treatment or hydrofinishing in order to improve color, oxidation stability, thermal stability, reduce foaming tendency and remove residual acidity of base oil. The conventional finishing treatments use many adsorbents such as activated or inactivated clays through percolation cylindrical filters, or by mixing. Clay...