The contamination parameters of basic operating fluids of combustions engines of mechanical vehicles: air, fuel and engine oil. It was shown that mineral (road) dust decides on the consumption of abrasive connection elements of an engine. The mechanism of abrasive wear of two cooperating surface of the piston-rings-cylinder abrasive connection element of the combustion engine was shown. It was shown that the dust grains of sizes dz equal to minimum hmin thickness of the oil film cause the largest consumption. It was shown that in the air purified, behind an air filter, there are always dust grains of sizes below 2÷5 μm. The effect of accelerated wear of a cylinder liner of the engine operated with a defective air filtration system was shown. It was shown that dust grains of sizes below 5 μm in the operating fluids are also the cause of the accelerated engine components wear. It was proven that (after replacing the filter cartridge), the operation period of a partition air filter (paper, non-woven fabric) is characterised by low efficiency and filtration precision. It was shown that contaminants in the fuel not only cause abrasive wear on the surfaces of the injection system elements but also erosive wear of injector elements.