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Introduction. During the combustion of diesel fuel in a diesel engine with an increased fuel supply, as a result of its incomplete combustion, soot particles are formed, which are either released into the atmosphere or inevitably enter the engine oil. Soot, polluting the engine oil, causes a change in its quality indicators. Soot is very small particles formed by a complex reaction mechanism in the flame of a fuel-rich region during the combustion of hydrocarbons in the absence of air, mainly consisting of a mixture of amorphous carbon and organic matter.Materials and methods. This paper presents the results of a literary review aimed at studying the ways of soot occurrence during the operation of diesel engines, its effect. The mechanical properties of diesel soot are also discussed on the surfaces of friction pairs and engine components.Conclusions. The soot content in engine oil will increase sharply in engines with exhaust gas recirculation, which leads to an increase in temperature in the friction zones and viscosity of the lubricant, as well as to the formation of deposits on hot parts. These processes occur due to the discharge in the crankcase space and the intensification of the intake of gases from the combustion chamber. Oil change intervals should be monitored at an increased rate of soot entering the engine oil.Scope of the study / opportunity. This type of study will help determine the causes of soot in a diesel engine, understand the consequences of using engine oil contaminated with soot particles.Originality / value. The conducted research can be the basis for the development of recommendations for improving the maintenance of internal combustion engines for enterprises that have cars with diesel engines at their disposal in order to increase the resource of power units and reduce operating costs.

Introduction. The reliability and service life of an engine is largely dependent on the quality of the engine oil. Without oil at the proper level of performance, an internal combustion engine can suffer from wear and tear, which in many cases can lead to engine failure. One of the factors in the loss of the quality level of engine oil is its contamination. For example, kinematic viscosity will gradually increase as the engine oil becomes contaminated with soot, dirt and sludge; or it may be oxidized. If the viscosity of the engine oil is too high, the engine must do extra work to overcome the increased viscosity resistance.Fuel and water dilution is one of the most common contaminants in diesel engines.Materials and Methods. The paper presents the results of a study of the combined effect of water and diesel fuel on synthetic engine oil at their various concentrations. The influence evaluation of contaminants on changes in the performance characteristics of the lubricant, such as: kinematic viscosity at 40° C (measurement was carried out on an automatic Stabinger SVM 3000 viscometer), base and acid numbers (values obtained using an automatic Titroline Alpha 20 Plus titrator), as well as concentration measurement elements - indicators of engine oil on an optical emission spectrometer with inductively coupled plasma of the iCAP 7000 series.Conclusions. The presence of contaminants in the engine oil leads to an increase in kinematic viscosity, during the operation of the engine oil, the value of its base number becomes less, and the value of the acid, on the contrary, increases. It is necessary to replace engine oils when the base number decreases by 50% or according to the balance of base and acid numbers.Scope of Study/Opportunity. This type of low temperature performance modelling provides insight into how the oil deteriorates and evaluates the change in oil performance during use.Originality/value. The study can be the basis for developing recommendations for improving the maintenance of internal combustion engines for enterprises that have cars with diesel engines at their disposal in order to increase the resource of power units and reduce operating costs.

Introduction. One of the main types of deposits in an internal combustion engine is an emulsion or sludge formed by water, decomposition of fuel residues and solid residues. The sludge usually settles on the colder surfaces of the engine, such as the bottom of the crankcase pan, valve chambers and upper boards. The main problem is that this type of deposits can be collected by the engine oil and transferred to areas such as the oil pump, intake valve or oil channels, where the sludge can interfere with the flow of oil and cause a failure of the lubrication mode. In addition to the disruption in the operation of the above-mentioned systems, the engine oil quality indicators are also undergoing changes for the worse.Materials and methods. To monitor the condition of the engine oil, it is necessary to determine the characteristics of its performance, such as: kinematic viscosity at 40 oC and at 100 oC, acid number, base number and determine the number of elements – indicators of additives and wear products contained in the engine oil. The viscosity was determined using a Stabinger SVM 3000 viscometer. It measures the dynamic viscosity and density of oils and fuels in accordance with ASTM D7042 and automatically calculates the kinematic viscosity, viscosity index and outputs the measurement results. The acid and base numbers were determined using an automatic titrator TitroLine alpha plus, and the presence of indicator elements in engine oil using an inductively coupled plasma optical emission spectrometer of the iCAP 7000 series, designed for analysis and determination of the number of indicator elements in liquid and solid samples.Results. The dynamics of changes in the performance characteristics of the Gazpromneft Diesel Ultra 10W-40 engine oil with an extended replacement interval, which is applicable for equipment operating in severe conditions, depending on the water content in the samples of this lubricant, was analyzed.Conclusion. The consequences that may occur due to water entering the engine oil are indicated.

Introduction. The effective operation of cars largely depends on the state of the engines, their downtime in maintenance and repair. Since the maintenance of modern engines is often reduced to the replacement of engine oil, the increase in the duration of its work significantly reduces maintenance costs and downtime in maintenance. Long maintenance-free operation of the internal combustion engines of automotive vehicles is directly related to the state of the engine oil used in this power unit. The aim of the paper is to show the features of the equipment operation with significant intervals of the engine oils’ replacement in order to increase the efficiency of its usage. The paper presents data on the features of the equipment operation when using high-quality motor oils with extended replacement intervals.Materials and methods. The authors conducted performance tests on the basis of MercedesBenzAxor, MercedesBenzActros cars. The manufacturer provided an estimate of the performance of engine oils. The main performance characteristics of motor oils were assessed using standard methods: kinematic viscosity was measured using a Stabinger viscosimeter, the base number was determined by an automatic AT-500 titrator, the content of wear products was obtained using an ASP-coupled emission spectrophotometer.Results. As a result, the authors presented data on the dependence of the changes in the main indicators of engine oil performance while the operating time and also substantiated the requirements for the volumes of fresh engine oil to compensate losses.Discussion and conclusions. The intermediate control allows detecting faults in the internal car engines, as well as providing the most accurate prediction of the resource of the lubricant under consideration. Therefore, the increasing of the engine oil change interval allows getting a significant economic effect.