The test apparatus is used for the standards test on properties preventing oxidation and corrosion of steam turbine oils, distillate fuel oils, extreme pressure lubricating oils, sledging tendencies of inhibited mineral oils, inhibited steam-turbine oils, hydraulic oils and circulating oils, etc. at an elevated temperature. This test is carried out in the presence of oxygen, water, copper, iron metals. The oil sample is contacted with oxygen in the presence of water and an iron-copper catalyst at 95 degree Celsius. The test continues until the measured acid number of the oil is 2.0mg KOH/g or above.