Abstract: A new type of semi-permanently usable oil filter controls the production of air bubbles, a cause of oil combustion, through a successful blending of oil filter and electronic control device by comprising a sensor means which senses the temperature, air bubbles and pressure of oil expelled from a pump in particular and the number of revolutions of an engine. A microcomputer which inputs data such as the dynamic rising pressure and falling-type stop pressure of uncompressed oil and data compared with the amount of oil passing under the pressure in the circulatory system according to the fuzzy theory. The computer compares the data of the sensor means and the peculiarity of Soliton wave based on the fuzzy theory. An actuator means is provided equipped with plural valves and plural relays which open/close the valves according to output from the microcomputer. Plural filters are installed so as to be opposed to the valves.