Careful grinding or honing is usually required in machining of gears in order to improve the machining quality of gear surface. Thus several grinding additives were used to formulate synthetic grinding lubricants similar to superior running-in lubricants. Experimental results show that the tooth surface of the produced oblique gear and steel worm becomes extremely smooth after grinding at a certain load for about a half to one hour. Especially, the gear surface finished with specially formulated grinding lubricant reaches mirror-like smoothness. The quality of the gear tooth can be improved by corrosive grinding, while the corrosive grinding time can be controlled by adjusting the quantity of the corrosive additives and the speed and load of the gears.