Chemical decarbonisation of diesel engine and its impact on engine oil degradation

<div class="section abstract"><div class="htmlview paragraph">Maximizing vehicle uptime and reducing maintenance costs are critical objectives in modern automotive systems, making efficient resource utilization a top priority. One of the key factors is engine oil life or degradation, which directly affects the engine performance, longevity, and overall vehicle efficiency/fuel economy. Most vehicles tracks engine oil life solely on a fixed mileage interval while few uses dedicated sensor, which is costly and requires service and maintenance.</div><div class="htmlview paragraph">As the engine oil degrades, it reduces Oil Total Acid Number (TAN) increases while Oil Total Base Number (TBN) decreases. It is recommended that maximum usable life of the engine oil is up to the crossover point between oil TAN and TBN (as the engine oil degrades). Vehicle driving pattern governs the occurrence of crossover points with respect to vehicle mileage. Based on this fundamental concept, an XG-Boost machine-learning algorithm is trained using vehicle Controller Area Network (CAN) channels and varying oil TAN and TBN parameters, derived from the vehicle-level measurement data available for the entire life cycle of engine oil in operating condition. The developed model based on CAN channels like engine rpm, engine torque, gear position, engine power, coolant temperature and odometer readings accurately predicts engine oil TAN and TBN parameter. The cross over point of TAN & TBN is accurately forecasted as seen in correlation results. An interactive user interface is designed and developed to display the deterioration in terms of remaining useful life of the oil to customers in vehicle driving condition.</div></div>

<div class="htmlview paragraph">A bench test was performed with Toyota 1500 cc OHC engines using a modified AMA mode in order to determine the change in performance, such as oxidation stability, thermal stability and antiwear performance, of gasoline engine oils as a consequence of their degradation. For the purpose of analyzing the relationship between the degradation of engine oils and their performance in detail, engine tests were performed without any new oil supply. The remaining performance of used oils was discussed in connection with both the degradation of engine oils and the depletion of oxidation inhibitors.</div> <div class="htmlview paragraph">The oxidation inhibitors, such as ZDTP, diarylamine and high molecular weight phenol, remaining in used oils were measured quantitatively with liquid chromatography. Oxidation stability, thermal stability and antiwear performance were measured with TFOUT, the hot tube test and the four ball test, respectively.</div> <div class="htmlview paragraph">It was found that the higher the temperature, the larger the rate of depletion of the oxidation inhibitors. In particular, the duration at high revolution speeds in which the sump temperature was raised up to 115° C accelerated the depletion of the oxidation inhibitors, resulting in the degradation of oils. The order of the rate of additive depletion was ZDTP > diarylamine > high molecular weight phenol, which corresponded to the thermal stability of these additives.</div> <div class="htmlview paragraph">The remaining oxidation stability of the used oils decreased gradually with the depletion of oxidation inhibitors; however, an adequate stability was observed even after the complete depletion of the additives. This might be explained as that the decomposition products of ZDTP could also act as an oxidation inhibitor in oils. The antiwear performance decreased rapidly within 50 h of the test and then decreased with the increase in the total acid number of the oils, probably because of corrosive wear. The thermal stability also decreased slightly around 150 h and then decreased rapidly when the total base number of the used oil dropped to less than 2.5 mgKOH/g.</div>

Effect of exhaust gas recirculation (EGR) contamination of diesel engine oil on wear

Engine oil degradation and tribological properties are strongly interrelated. Hence, understanding the chemical processes resulting in additive depletion and degradation products is necessary. In this study, in-service engine oils from petrol and diesel vehicles were analyzed with conventional and advanced methods (mass spectrometry). Additionally, the effect of the utilization profile (short- vs. long-range) was studied. Petrol engine oils generally showed accelerated antioxidant and antiwear degradation and higher oxidation, especially in the case of a short-range utilization profile, which can be attributed to the higher air-to-fuel ratio (more rich combustion) compared to diesel engines. A detailed overview of oxidation and nitration products, as well as degradation products resulting from zinc dialkyl dithiophosphate and boron ester antiwear additives, diphenylamine antioxidants and salicylate detergents is given. A side reaction between oxidation products (aromatic carboxylic acids) and the boron ester antiwear is highlighted. This reaction was only detected in the petrol engine oils, where the oxidation products were measured in a high abundance. However, no side reaction was found in the samples from the diesel vehicles, since there the aromatic carboxylic acids were largely absent due to lower oxidation.

The performance of the engine oil is affected over time by the different parameters such as combustion products such as soot particles, carbon, unburned fuel, and unburned hydrocarbon (UHC). The engine oil degradation was analysed by using Transmission Electron Microscopy (TEM), Thermogravimetric Analysis (TGA) and Fourier Transform Spectrometry (FTIR). In this work, it is indicated that the number of primary particle (npo) increased with long time of engine operation (30 days) compared with short period of engine operation (10 days). Besides, the size of primary particle (dpo) is bigger by (33nm) from combustion of 30 days on engine operation with respect to the 10 and 20 days by 28 nm and 31 nm, respectively. The high levels of presence soot particles in the engine oil are need a higher temperature for degradation. Further, it is found that the 400 °C is the maximum temperature for weight loss in case of fresh oil, while goes to 450 °C for used oil (soot in oil). From FTIR results, the concentration of soot contamination in lubricating oil increased with long time of engine operation.

This work aimed to bridge the gap between engine oil degradation, in particular zinc dialkyl dithiophosphate (ZDDP) deterioration, its effect on tribofilm formation, and its eventual impact on friction and wear. Artificial oil alteration of a commercial engine oil SAE 0W-20 was used to produce a series of altered oils that were subjected to high resolution mass spectrometry in order to identify ZDDP degradation products and their abundances over time. It was found that ZDDP was depleted at an early stage of alteration by the replacement of its sulfur atoms by oxygen atoms and the release of the alkyl side chains. As final products of ZDDP deterioration, sulfuric and phosphoric acid were identified. Selected oils were subjected to tribometrical experiments consisting of an oscillating ball-on-disc contact. ZDDP concentration as well as the type and abundance of ZDDP degradation products in the oils directly influenced tribofilm formation and consequently friction and wear. However, the superior tribological performance of the fresh engine oil could not be regained with any of the artificially altered oils. X-ray photoelectron spectroscopy revealed that sulfur occurred mainly in sulfide state in the tribofilm formed from fresh oil. With increasing degree of oil degradation, the sulfate state became more dominant. By trend, the amounts of sulfur, phosphorus, zinc and calcium declined with increasing degree of oil degradation, indicating that tribofilm formation had become increasingly difficult.

<div class="section abstract"><div class="htmlview paragraph">As one of spark ignition (SI) engine solutions to improve fuel economy while maintaining drivability, concept of combing turbocharging and direct injection (DI) fuel injection system with engine down-sizing has increased its application in the market. Abnormal combustion phenomena referred to as Low Speed Pre-Ignition (LSPI) has been recognized as potential restriction to improve low speed engine torque that contributes fuel economy improvement. As reported in the part 1 [<span class="xref">1</span>], the study showed that engine oil composition had significant influence on the frequency of LSPI in both preventive and contributory effects.</div><div class="htmlview paragraph">Further investigation was conducted to evaluate engine oil formulation variables and other factors that may have influences on the LSPI, such as engine oil degradation.</div><div class="htmlview paragraph">Engine test that consisted of 2 phases was designed in order to confirm the correlation between LSPI frequency and engine oil degradation. The LSPI frequency measurement phase and engine oil degradation operation phase were conducted alternatively without changing engine oil. It was observed that the engine oil degradation increased the LSPI frequency.</div><div class="htmlview paragraph">Several different types of engine oils, including both experimental oils that represent possible chemical & physical properties found in the market and a few commercially available engine oil products that meet industry standards, such as API S category and ACEA specification, were also evaluated to understand the feasibility of engine oil that has LSPI prevention performance.</div><div class="htmlview paragraph">The test results showed it is feasible to formulate the engine oil that reduces LSPI significantly while maintaining basic engine oil performances.</div></div>

Lubricating engine oil which is used in vehicles and machines to keep them running smoothly, is frequently released during automobile engine servicing or illegally dumped, posing a significant environmental threat because it is less volatile than other types of petroleum fuels and remains in the soil for longer periods of time. To solve this problem, new environmentally friendly techniques must be created. Considering the same, the current investigation, was carried out to screen and evaluate the oil-degrading capability of bacterial isolates from oil-contaminated soil collected from different sites of Udaipur city. The isolation was done on Luria-Bertani agar using the pour plate method. The primary screening of the isolates for used engine oil degradation was done on Bushnell Haas mineral salt agar medium using the spot inoculation method. The 2,6-DCPIP (2,6-Dichlorophenol indophenol) indicator was used to determine the oil degrading efficiency of isolates. A total of ten soil samples contaminated with used engine oil were collected from two distinct locations of Udaipur city. A total of seventy eight bacterial isolates were recovered using pour plate method from various soil samples on LB (Luria-Bertani) agar at 370C after 24 hours of incubation period. Twelve bacterial isolates out of seventy eight showed zone of clearance, indicating oil degrading capability. The diameter for zone of clearance of 12 isolates ranged between 5 to 15 mm. All 12 isolates demonstrated DCPIP decolorization. Color reduction percentage ranged from 68.66 % to 98.57 % for 12 oil-degrading bacterial isolates. Isolate ODB 29 showed the highest color reduction (98.57 %). These isolates may be explored for their possible use in bioremediation.

On the problems in determining the stability of lubricants. (in German) : G. H. Göttner, Materialprüfung, 5 (9) (1963) 331–335; 4 figs., 10 refs

The present research was undertaken to isolate and characterize petroleum hydrocarbon degrading microbes from ship-breaking yards at Vatiary and Kumira coast in Chittagong. Twenty different petroleum hydrocarbon contaminated composite samples were collected and the total bacterial count was found to vary between 2.7×103 cfu/ gm and 1.77×107 cfu/ gm. Ten isolates were finally selected through secondary screening by Bushnell-Hass mineral salt medium using kerosene, diesel and engine oil as carbon source. They were provisionally identified and found closely related to the species Listeria monocytogenes, Staphylococcus aureus, Pseudomonas alcaligenes, Listeria grayi, Bacillus pasteurii, Bacillus badius, Bacillus cirroflagellosus, Bacillus circulans, Bacillus brevis and Citrobacter freundii. Greasy spot test was used as the primary indicator of microbial degradation of kerosene, diesel and engine oil. A more specific experiment was carried out to estimate the rate of degradation by the isolates. The highest (96.8%) degradation of diesel was shown by B. brevis, followed by 92%, 88.8% and 84.8% of diesel degradation by the strains of P. alcaligenes, B. cirroflagellosus and C. freundii, respectively. The highest degradation of kerosene (78.26%) and engine oil (43.97%) by S. aureus and L. monocytogenes respectively, were also observed. Keywords: Microbes; Petroleum hydrocarbon; Degradation DOI: http://dx.doi.org/10.3329/bjm.v27i1.9161 BJM 2010; 27(1): 10-13

The analysis of used engine oils from industrial engines enables the study of engine wear and oil degradation in order to evaluate the necessity of oil changes. As the matrix composition of an engine oil strongly depends on its intended application, meaningful diagnostic oil analyses bear considerable challenges. Owing to the broad spectrum of available oil matrices, we have evaluated the applicability of using an internal standard and/or preceding sample digestion for elemental analysis of used engine oils via inductively coupled plasma optical emission spectroscopy (ICP OES). Elements originating from both wear particles and additives as well as particle size influence could be clearly recognized by their distinct digestion behaviour. While a precise determination of most wear elements can be achieved in oily matrix, the measurement of additives is performed preferably after sample digestion. Considering a dataset of physicochemical parameters and elemental composition for several hundred used engine oils, we have further investigated the feasibility of predicting the identity and overall condition of an unknown combustion engine using the machine learning system XGBoost. A maximum accuracy of 89.6% in predicting the engine type was achieved, a mean error of less than 10% of the observed timeframe in predicting the oil running time and even less than 4% for the total engine running time, based purely on common oil check data. Furthermore, obstacles and possibilities to improve the performance of the machine learning models were analysed and the factors that enabled the prediction were explored with SHapley Additive exPlanation (SHAP). Our results demonstrate that both the identification of an unknown engine as well as a lifetime assessment can be performed for a first estimation of the actual sample without requiring meticulous documentation.

ABSTRACTEngine oil contamination, degradation and wear of engine components occurs mainly due to fuel dilution, oxidation and blow-by. This contamination accelerates the wear of engine components and also decreases the useful service life and performance of engine oil. Failure of engine oil can cause engine component failure. The three major contaminants which initiate engine oil degradation and engine component wear are soot, water and particles. Soot contamination in lubricating oil is responsible for oil thickening and engine wear. Water emulsifies the oil and the wear debris generated further enhance the wear rate as three body abrasive process. This paper reveals the role of biofuels in engine oil degradation in terms of contamination, fuel dilution, oxidation and blow-by and wear. This paper provides a platform to understand the tribological relationship between lubricating oil and engine components.

<div class="section abstract"><div class="htmlview paragraph">The Global Fuel Economy Initiative in 21<sup>st</sup> session of COP21 to the UNFCCC aims to develop 50 percent more efficient automobiles by the year 2050.This initiative has enhanced interest in fuel economy improvements and emission reduction using novel engine-related technologies and fuel efficient engine oil. Low viscosity grade engine oils have demonstrated the potential to improve the fuel economy by reducing the friction and lowering the greenhouse gases. In this context of developing fuel efficient engine oils, this study focuses on establishing the validity of an in-house short duration test protocol to differentiate engine oils from a fuel economy aspect and also attempts to relate reduced exhaust emissions. In the present study, low viscosity grade oils - SAE 0W-20, SAE 5W-30 and SAE 20W-40 as the baseline oil, were selected for assessing engine oil effects on fuel economy of diesel engines. Effects of viscosity on engine performance with respect to power, fuel economy and emissions were investigated by conducting fuel economy engine tests on a single cylinder Petter AV1 diesel engine. In the results, higher fuel economy and lower CO<sub>2</sub>, HC and NOx emissions were observed using lower viscosity engine oils compared to higher viscosity engine oils. The analysis reveals that lower viscosity engine oils indicate favorable prospects in terms of enhanced fuel economy and reduced exhaust emissions due to engine oil.</div></div>

Engine oil degradation impacts the operation and performance of an internal combustion engine. As a result, it is crucial to compare the degradation level of engine oils, with a particular emphasis on kinematic viscosity, oxidation, nitration, and critical oil testing characteristics. Suppose engine oil changes too soon without first calculating its remaining usable life. In that case, it wastes already scarce resources and has an unfavourable environmental influence. Engine performance may suffer if oil is changed too late and is of poor quality. In the current research, oil testing is performed on vehicles due to maintenance to find the best moment for changing engine oil. Oil samples were taken randomly from cars that came to an authorized service facility for maintenance, comprising a wide range from the first to the fifth servicing. Oil samples were initially evaluated in a laboratory using a viscometer and Fourier transform-infrared spectroscopy in conformity with industry standards. The samples were then evaluated using an integrated sensor system developed and built by the authors. The determination coefficient R2 = 0.97 showed a significant positive association between major engine oil degradation characteristics such as kinematic viscosity, oxidation, and nitration at reasonable sensitivity. Approximately 8% of the total gathered samples were useable. The research identifies several oil degradation sensor systems that give low-cost, on-site convenient options for oil condition monitoring and predicting the remaining usable life of engine oil.

Today, modern tribodiagnostics offers sophisticated analyzes of motor oils with fast and accurate results. However,Today, modern tribodiagnostics offers sophisticated analyzes of motor oils with fast and accurate results. However,finding the causes of some undesirable processes of engine oil degradation often requires long-term monitoring of the operatingfacility. In this case, it was a problem of diesel engine oil in the Citroёn Jumpy 2.0 HDi service minibus, which has been in useby the Department of Mechanical Engineering (Armed Forces Academy of General M. R. Štefanik, Demänová) for more than13 years. The fuel system (conditioners of injectors) on this vehicle has also been monitored for a long time in the period 2019-2021, an article about it was also published in the journal Science & Military (No. 2 / Vol. 14/2019). The cadets of theDeptartment of mechanical engineering Armed Forces Academy of General M. R. Štefanik, were also involved in the diagnosticprocess. In parallel with the fuel system, the quality of the engine oil was regularly monitored in the time interval 20.1.2020 -22.4.2021 at a start of 2185 km from the last oil change. During this monitoring, a very rapid degradation of engine oil wasfound in some parameters, which is atypical during normal vehicle operation. This article discusses the measured results andpossible causes of this adverse event.