Method for reforming lubricating oil and lubricating oil

A method for reforming a lubricating oil which comprises holding stably a container ( 6 ) containing a lubricating oil ( 5 ) on a stand ( 4 ) being insulated to the earth with four high-voltage insulators ( 3 ), applying an electrostatic potential of 30 to 50 voltages by the use of an electrostatic charge generating device ( 7 ), to thereby charge electrons to the lubricating oil ( 5 ). The above charge of electrons converts an unsaturated hydrocarbon ( 1 a ) and an aromatic hydrocarbon ( 2 a ) in the lubricating oil ( 5 ) to a saturated hydrocarbon ( 1 b ) or ( 2 b ) and a naphthenic hydrocarbon ( 2 c ), which reduces the viscosity of the lubricating oil. Accordingly, the use of the lubricating oil ( 5 ) in an internal combustion engine lowers the friction resistance therein, which leads to the decrease of the fuel consumption of the engine. The method allows, therefore, the enhancement of fuel economy, in combination with the suppression as much as possible of oxidation of a lubricating oil itself.