Abstract: A coating of tetrafluoroethylene or other suitable material is present in the heating element of a bypass oil refining device for the purpose of substantially preventing deposit of carbon or carbonaceous material on the heating element during operation of the device. The heating element is located in a vaporization chamber. The bypass oil refining device incorporates a pressure control valve to shut off flow of oil from a mechanical filter to the vaporization chamber when the oil pressure in the mechanical filter exceeds a predetermined value. An externally adjustable flow control valve is also incorporated in the device to permit control of the rate of flow of the oil from the mechanical filter to the vaporization chamber. Water and fuel vapors which are distilled out of the oil in the vaporization chamber are released from the vaporization chamber through a vent and check valve, and are absorbed as condensates in a suitable, absorbent material. The absorbent is preferably placed into a disposable cartridge.