Lubricating oil as well as preparation method and application thereof

The invention discloses lubricating oil which is prepared from base oil, graphene, self-emulsifying ester, dimethyl sulfoxide, a composite additive, a high-temperature antioxidant, a metal deactivator, a viscosity modifier and an anti-foaming agent. The invention has the following beneficial effects: the added graphene has the advantages of energy saving, low oil consumption and low noise; the product belongs to a phosphorus-free, low-sulfur and low-ash energy-saving and environment-friendly product; as the nano boron ceramic is small in particle size and high in hardness, peak clipping and valley filling can be realized, unit load can be reduced, oil temperature can be balanced, a new friction surface can be finely ground, a scratched surface can be self-repaired, local rolling friction can be realized, resistance can be integrally reduced, power can be exerted, oil consumption can be reduced, emission can be reduced, and the nano boron ceramic can be completely or partially applied to occasions for replacin