Introduction: At the present time there are, on the market, numerous lubricating aids which are designed to improve the lubricating qualities of the various mineral lubricating oils, especially those intended for automotive use. The manufacturers of some of these make statements concerning them that to any fair-minded individual are startling. With this in mind, it has been the purpose of the author to try to verity these claims or else disprove them. It would be impossible in the time allowed to test allot these aids; so a representative few were chosen which covered the field quite thoroughly. From the results shown by the use of these aids in an internal combustion engine, as well as those shown by the physical property tests in the laboratory, it seems as though their suitability for industrial use would be demonstrated. In other words, the results should show which of the arguments put forth by the manufacturers of the various products are of sound basis and which are stated merely for the sake of advertising and publicity. / Master of Science