The defect structure study of the subsurface zones emerged during the sliding of two metal surfaces under lubrication conditions was performed for two different oils. The copper samples obtained in the pin-on-disc tribometer were the subject of the positron beam and conventional Doppler broadening experiments. During the sliding of two metals with a lubricant on the surface or in the depth up to ca. 10 nm appeared a layer which properties detected by positrons were visibly different than those of the reference sample surface or surface which was slid without lubrication. One could not exclude that in this region open volume defects of large radius came into being. With conventional positron annihilation measurements it was possible to achieve the vacancy profile in the region at the depth in the range 20 mum - 350 mum.