PURPOSE: To provide the titled apparatus free from the leak of oil, controllable by simplified electrical means, and composed of a bottom-closed cylindrical casing, a plurality of porous permanent magnets arranged in said casing, and a fuel-oil rotor 6 furnished with an inlet pipe for the oil to be treated, an outlet pipe for the treated oil and an indirect rotating means.

CONSTITUTION: A plurality of disc-shaped porous permanent magnets 3 are attached to the inner wall of the closed cylindrical casing 2 having closed ends continuously along the length of the casing 2 so as to exert attractive forces with each other. Fuel oil such as light oil pressurized to about 0.5W3.0kg/cm2 is introduced through the inlet pipe 4 into the fuel oil reformer 1, and the rotor 6 provided with the blades 10 is rotated to rotate the oil at a rate of about 500W 3,600 revolutions per minute in the casing 2. The oil crosses the magnetic line of force at a high speed by this process, and reformed to an activated, low-viscosity fuel oil and discharged from the outlet pipe 5. The oil-leak can be prevented by attaching the follower magnets 8 to the rotor 6, and the driving magnets 9 to the motor 7, and coupling the driving magnets with the follower magnets through the wall of the casing 2.