FIELD: measuring equipment.SUBSTANCE: method for predicting indices of thermo-oxidative stability of lubricating materials is proposed at which a sample of lubricant is tested in presence of air with mixing of constant mass at least at three temperatures selected depending on the main base, designation and group of operational properties, for a period of time characterizing the same degree of oxidation. A sample of oxidized lubricant is taken at regular time intervals and evaluation of oxidation process is carried out. According to the invention, optical density, evaporation and thermo-oxidative stability coefficient are determined for evaluating the oxidation process, graphical dependencies of these factors are plotted depending on time and three selected test temperatures. The time to reach the selected values of the thermal-oxidative stability values from the minimum to the maximum value at each temperature is determined. The decimal logarithm of time to reach the selected values of the thermo-oxidative st
