shaped valve 18 is inserted into the oil filler opening 59 and the valve 18 is opened to return the oil in the inspection tank 6 to an oil sump not shown of the automobile on the other hand however if it is found that the degree of oil contamination or deterioration is high and oil change is required then the two way valve 26 is switched over so as to establish communication between the flexible tubes 30 33 and the changeover valve 53 is operated to reverse the rotation of the gear pump 27 thereafter the pistol shaped valve 28 with its tip portion inserted into the oil filler opening 59 is triggered to open so that the fresh oil in the metering tank 7 is supplied through the oil filler opening 59 to the oil sump of the automobile 56 at a desired quantity while careful attention being paid to the reading of scale marks 12 on the metering pipe 10 to discharge from the inspection tank 6 the oil contaminated or deteriorated to such a degree as unsuitable for use the three way valve 13 is shifted to establish communication between the flexible tubes 22 and 24 and the changeover valve 50 is operated to reverse the rotation of the gear pump 14 whereby the contaminated or deteriorated oil in the tank 6 is discharged into the waste oil reservoir 4 by way of flexible tube 25 gear pump 14 flexible tube 24 three way.