The acid value, MPC value, and moisture value improved more than the new oil standard value within about two months after the SEC-300M was put into operation. However, as mentioned above, it seems that the EC filter removes the soluble contaminants and the solubility of the oil increase, so that the sludge and varnish adhered to the inside of the pipe and the inside of the pipe are increased. Since then, the continuous operation of SEC-300M has completely dropped the pollution level.