This work conducted reasearch of the effects of adding graphene as a filler in the PAO oil. Research has been focused on achieving improved thermal properties with the lowest possible concentration of graphene in order to create homogeneous and stable suspension of nanoparticles in the base fluid. Experimental section is divided into two phases. In the first phase seven nanofluids were prepared with different surfactants (PAT) for the purpose of testing compatibility between PAT and PAO 4 oil with graphene. In the second phase, seven nanofluids were prepared with just one surfactant, which showed the best results, in this case the DPS. The goal of the second phase is the examination of the effects that the concentration of added graphene has on different nanofluids properties such as stability, contact angle, viscosity, wear properties and thermal conductivity. To determine the stability of nanofluids sedimentation test was used both visual and instrumental method (UV / VIS spectrophotometry). The visual method involves photographing specimens through 60 days, then studying the images. In order to determine the stability with advanced security, nanofluids were shot in the UV / VIS absorption spectra of samples, and stability has been portrayed in the form of dispersion of graphene in the base fluid. Increasing the ratio of the polymeric surfactant DPS, it raises the viscosity, and thus increases the stability of the system. Results of measuring the contact angle showed that the metal and glass surfaces close the smallest contact angle with the nanofluid. Contact angle on teflon surface is higher due to an increase in surface energy. Thermal conductivity of all samples of nanofluids is growing in comparison with the base fluid and the wear test shows that wear is a lot smaller with nanofluid, than with base PAO fluid.