In recent times, many specially engineered diesel engines built in the 1980s are still used in different areas, for which the suggested engine oils are no longer available. These engines are operated reliably in military combat vehicles, electricity generators, and tracked machinery, thus it is essential to examine what engine oils are suitable for their operating conditions and may be used as their engine oil. The aim of our research is to conduct the tribological examination of an oil sample taken from a V-6M type naturally aspirated Diesel engine and the oil prescribed by the manufacturer. After evaluating the results, we determine which type of oil is applicable in the engine to achieve safe operation and a long lifetime.

Detecting the engine failures of the continuous track military vehicles is challenging because their engines are always built-in narrow places covered with armored plates. In the case of the older engines, modern computer diagnostics cannot be used for failure analysis; the solution for these tasks is the visual analysis with the engine disassembly. A possible cost-effective failure analysis method can be the tribological and chemical analysis of the used oil from the engine, which can eliminate the engine disassembly work and as the results of the chemical oil analysis can also provide information about possible fuel or cooling water dilution or the increased wear of engine components. The main goal of this article is to present the failure analysis method through the tribological investigation of the engines of two PTSZ-M type medium-tracked amphibious military transport vehicles.