A SYSTEMS APPROACH TO STUDYING THE MECHANISM OF DEPOSITS FORMATION IN DIESEL LUBRICATION SYSTEMS

doi: 10.65402/npnh.2025.11.004
UDC: 665.7.035 + 001.891.57
Received: 25.10.2025
Pages 23-34

Abstract. This article presents a proposed mechanism for deposit formation in diesel lubrication systems from the standpoint of micelle formation, which is based on reactions of hydrocarbon oxidation in motor oil, micelle formation and solubilization, polycondensation, coagulation, and sedimentation of motor oil oxidation products. The majority of primary oxidation products form in a thin film of oil on the cylinder liner wall, which comes into contact with hot gases during the expansion stroke. These gases, along with the oil, enter the diesel crankcase during subsequent piston strokes. In the crankcase, the engine oil oxidation products are solubilized by micelles of detergent-dispersant additives. When the critical concentration of polar oxidation products within the micelle core is exceeded, the protective diffusion layers are destroyed, leading to the coagulation and sedimentation of solid particles, forming low-temperature deposits in the crankcase. Due to intensive mass transfer, some of the oxidation products are removed from the crankcase and, along with the oil, reach hot components of the cylinder-piston group (CPG). At elevated temperatures, the strength and integrity of the surface protective layers formed by detergent-dispersant additive micelles are compromised, leading to the coarsening and release of dispersed phase particles from the system, which are adsorbed on engine components in the cylinder-piston group area. Adsorbed dispersed phase particles are firmly held on the metal surface and, due to the high temperatures, undergo thermal-oxidative transformations, namely condensation and coking, resulting in the formation of insoluble compounds that form dense, difficult-to-remove high-temperature deposits.

Key words: motor oils, diesel, deposits, micelle formation, deposit formation mechanism

For citation: Prokoptsova M.D., Likhterova N.M., Shatalov K.V., Volgin S.N. A systems approach to studying the mechanism of deposits formation in diesel lubrication systems. Neftepererabotka i neftekhimiya. 2025, no. 11, pp. 23-34. (In Russ.) DOI 10.65402/npnh.2025.11.004.