A new concept was developed for evaluating the antiwear properties of lubricants - based on the value and distribution of the micromechanical characteristics in the near-surface layer deformed by friction. A diagnostic parameter for wear-fatigue processes is proposed: the micromechanical strength characteristic gradient, expressed in terms of the structural state criterion, formed in the near-surface layer of steel parts as a result of friction. This criterion can be used for assessing the antiwear and antiscuff properties of lube oils. Oils with high antiwear characteristics form minimal positive micromechanical property gradients it? the near-surface layer of the metal.