A series of cooperative interlaboratory tests (round robins) was conducted in 1997, 1998 and 1999 by the DIN 51834 Working Group on Tribological Tests in Translatory Oscillation Apparatus. The statistical analysis of these test results shows the influence of cleaning solvent, machine model and evaluation criteria on the tribological properties of the lubricants tested. Coefficients of friction and wear results are ranked according to the effects of ten different cleaning solvents, where isopropanol gave the lowest values and isoparaffin solvents the highest. The effect of machine model on coefficients of friction varied from about 0.2 % to 0.9 % of the average. Wear results were not affected. The tests also showed that the seizure criteria and methods of measuring wear required for in the test procedure do not provide a suitable measure of the tribological properties of some lubricants.