Improving the efficiency of agricultural land use depends primarily on the return on investment and rational use of resources. Agricultural machinery (tractors, aggregates, machines, etc.) is one of the important resources. The use of agricultural tractors in conditions of high air dustiness leads to the ingress of abrasive particles into the internal cavities of the transmission, which causes increased wear of parts and impairs the performance properties of transmission oil. This process is mainly due to transmission gas exchange with the environment, occurring with insufficient tightness of power transmission aggregates. Studies were conducted to determine the magnitude of transmission gas transmission, changes in the tightness of transmission cavities, as well as the accumulation of mechanical impurities and iron in the transmission oil during the operation of the tractor. The BELARUS-80.1 tractor was used as an object of the study. Studies were carried out both in bench and in operational conditions. To assess the tightness of tractor transmissions, an installation was developed that allows determining the qualitative and quantitative indicators of tightness. Based on the research, it was found that the change in the temperature and air volume contained in the transmission cavity has the greatest effect on the gas exchange rate. So, when the transmission temperature of the tractor BELARUS-80.1 changes by 1ºC, the transmission gas exchange with the environment is 0.5-0.6 dm 3. It was established that, while improving the tightness of the transmission by 10-15 %, the wear of parts, estimated by the change in the mass fraction of iron in oil, decreased by 15-17 %.