The present invention relates to a vegetable oil, particularly a lubricating vegetable oil, treated, for example, by electrical discharges, characterised in that it has a dynamic viscosity of between 700 mPa.s and1400 mPa.s and a relaxation time of less than or equal to 200 s, measured at 40°C by a cone-plate viscometer according to the standard ISO 2884-1.