It is shown that the dependence of surface tension of oil on temperature and content of additives in it can be used to determine their concentrations even in the case when these additives have identical metals in their composition. For oil with a mixture of barium containing additives SB-3 and BFK emperical dependencies are selected which allow calculation of the concentration of these additives according to the magnitude of surface tension of oil, determined at temperatures 15 and 20C. Author
Edited machine trans. of Prisadki k Smazochnym Maslam (USSR) n2 p207-210 1969, by Charles T. Ostertag.