Abstract. The present paper describes a simple four balls testing device adapted for a classical drilling machine, using standard methodology meant to evaluate the lubricating properties of lubricants. The advantage of the method consists in the possibility of using any type of balls and a special device adapted to a common drilling machine. The evaluation of anti-wear lubricants properties can be done by comparing the contact scar dimension obtained experimentally, following the procedure described in EN ISO 20623:2003 international standard. The contact scar diameter is measured using an optic microscope equipped with a camera and specialized software, by comparing the scar with a known body dimension. Some experimental results obtained for the contact between four 12.7 mm bearing balls lubricated with grease are presented as well. The contact scar dimension-load dependencies are similar to those presented in literature and therefore validate the experimental setup. IntroductionTribology failures determine about 30 percent of all failures in mechanical systems, [1]. This amount can be minimized by proper selection of lubricant, [2], the key element for proper system running. Knowledge of the anti-wear properties of lubricants is a very important aspect in system running. These properties can be determined by using special test machines and following a well specified procedure which involves specific testing equipment. This can be a real problem for small and medium factories, because it implies additional costs and investments that are unjustified if the low number of tests is considered. In such small manufactories, even to order of the tests from a specialized laboratory that owns the proper testing machine, raises costs and time problems. Usually, only comparing the anti-wear properties of two lubricants is required, in order to adequately choose the best suited one. This comparison is best done using the four balls test.The four balls tests are used to measure the anti-wear and extreme pressure properties of lubricants by monitoring the evolution of wear scars. By comparing the results for different lubricants, it can be determined which is the best lubricant that can be used in certain conditions. The test procedure is described in EN ISO 20623:2003 international standard, [3], and consists in a four balls special tester in which an upper rotating bearing ball is in contact with 3 lower bearing balls, fixed and immersed in lubricant. The upper ball is held in a steel chuck and rotated with 1450-1500 rpm by an electric motor. The lower bearing balls are held against each other in a steel cup. The ensemble is supported by a disc which rests on an axial bearing that allows horizontal displacements and self alignment between the upper rotating ball and the lower balls. The load is applied vertically by a load lever, in order to press the upper ball against the lower balls with a controlled load.