The use of the IAE gear test machine (made in England) for evaluation of the fatigue wear (pitting) of gears and bearing elements is discussed. The antiscoring and antipitting properties of gear and transmission oil were studied in an IAE test machine. In order for the data to be reproducible it was determined that a value of contact stress of 2400 MPa was necessary. The performance of a wide variety of oils in the tests are described. The tests showed that the IAE machine could be used to evaluate the most important property of gear and transmission oils: their ability to mitigate fatigue wear of heavily loaded gear transmissions.