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Engine oil is critical to tractor engine performance. Engine designers recommend farmers change engine oil depending on recommendations by engine manufacturers. Engine manufacturers did not take into account different tasks often performed by tractors in fields, like tillage or seeding. Farmers do not have certain criteria to determine when engine oil must change. The only criteria to change engine oil is the physical /chemical method, which takes at least one week to obtain oil results. It is a waste of time to wait one week to get the results. There will be a lot of mechanical engine problems if oil is not changed. These engine oil problems cost farmers a lot of money. The aim of this research is to use new technology that could be contributed to solving these technical difficulties. Terahertz technology was used to determine engine oil characteristics by measuring refractive index and absorption coefficient on different conditions. Four experiments were performed to identify the ability of terahertz technology on various engine oil grades, engine oil types, and engine oil contaminants by using terahertz time-domain spectroscopy (THz-TDS). The first experiment was classifying gasoline engine oils of various viscosities by using THz-TDS. The range of 0.5–2.0 THz was evaluated for distinguishing among gasoline engine oils of three different grades (SAE 5W-20, 10W-40, and 20W-50) from the same manufacturer. ANOVA results confirmed a highly significant difference (p<0.0001) in refractive index among each of the three oils across the 0.5–2.0-THz range. Linear regression was applied to refractive index data at 0.25-THz intervals from 0.5 to 2.0 THz to predict kinematic viscosity. The refractive indices of these oil samples were promising for identification and distinction of oil grades. The second research identified three levels of water contaminants 0.0%, 0.1% and 0.2% inside diesel engine oils, grade SAE 15W-40, by utilizing THz-TDS in the range of 0.5 to 2.0 THz. The 0% water contamination level had the lowest absorption coefficient, while 0.2% water had the highest absorption coefficient. The refractive index of 0% water was the lowest and 0.2% water was the highest across the THz range. The refractive indices of these oil samples were promising for discrimination of water contamination. The third experiment demonstrated the possibility of identifying gasoline in engine oil (SAE 5W-20) which was contaminated with four rates (0%, 4%, 8% and 12%) of gasoline fuel and were measured by using THz-TDS. For both refractive index and absorption coefficient of the single cuvette method, ANOVA and Fisher results illustrated that there were highly significant differences (p < 0.0001) among each of the gasoline contaminant levels across the 0.5-2.5 THz range. The 2.5 THz frequency was the best to predict fuel contamination based on refractive index, and 0.5 THz was the best frequency for absorption coefficient. The fourth experiment illustrated the potential of THz-TDS to detect viscosity at 40 °C and TBN changes in gasoline engine oil (SAE 5W-20) due to thermal oxidation (TO). For refractive index, ANOVA and Fisher results showed that there were highly significant differences (p < 0.0001) among each of the TO times across the 0.51 - 2.48 THz range. Refractive index was used to predict TO time, and the 1.25 THz frequency was best to predict viscosity at 40°; for TBN, 2.25 THz was best.

Solids-stabilized water-in-oil emulsions have been suggested as a drive fluid to recover viscous oil through a piston-like displacement pattern. While crude heavy oil was initially suggested as the base oil, an alternative oil ? used engine oil was proposed for emulsion generation because of several key advantages: more favorable viscosity that results in better emulsion injectivity, soot particles within the oil that readily promote stable emulsions, almost no cost of the oil itself and relatively large supply, and potential solution of used engine oil disposal. In this research, different types of used engine oil (mineral based, synthetic) were tested to make W/O emulsions simply by blending in brine. A series of stable emulsions was prepared with varied water contents from 40~70%. Viscosities of these emulsions were measured, ranging from 102~104 cp at low shear rates and ambient temperature. Then an emulsion made of 40% used engine oil and 60% brine was chosen for a series of coreflood experiments, to test the stability of this emulsion while flowing through porous media. Limited breakdown of the effluent was observed at ambient injection rates, indicating a stability of the emulsion in porous media. Pressure drops leveled off and remained constant at constant rate of injection, indicating steady-state flows under the experimental conditions. No plug off effect was observed after a large volume of emulsion passed through the cores. Reservoir scale simulations were conducted for the emulsion flooding process based on the emulsion properties tested from the experiments. Results showed significant improvement in both displacement pattern and oil recovery especially compared to water flooding. Economics calculations of emulsion flooding were also performed, suggesting this process to be highly profitable.

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The goal of this research is to study the neutralization of sulfuric acid by engine oils, and more specifically study how the presence of different oil additives affects the acid-neutralizing performance of engine oils by using capillary videomicroscopy. Nowadays the formulation of engine oils has been changing due to a trend of different regulations around the world that seek to diminish the emission of atmospheric pollution from all types of vehicles driven by internal combustion engines. In the particular case of large marine ships powered by low-speed two-stroke diesel engines, pollutant emissions are high given that the marine fuel they use can contain up to 4.5 wt. % of sulfur. But this sulfur content cap in marine fuel is bound to diminish dramatically during the ongoing decades due to regulations and therefore, the industry is coming up with new engine oil formulations accordingly as to comply with these changes. Here a technique called capillary videomicroscopy was used to study new changes to engine oil formulations. The reaction and dispersion of a sulfuric acid micro-droplet into formulations of marine cylinder lubricants (MCL) was studied by microscopically observing and measuring the shrinking of a micropipette-produced droplet in real time. It was found that MCL formulations having a base number (BN) of 40 had an acid-neutralizing performance comparable to those of having BN 70. On the other hand, the addition of fatty alcohols as final additives to MCL formulations so as to boost the MCL’s acid neutralization performance was found to be slightly effective although phase separation due to alcohol insolubility in MCL at room temperatures and other resilient phases formed upon reaction can be detrimental, hence the use of fatty alcohols for boosting any MCL formulation cannot be generalized and should be studied for each formulation. In the case of passenger car motor oils (PCMO), substitution of traditional oil additives by new sulfur-free additive species is driven by the need to prevent the catalytic converter's poisoning by eliminating any sulfur present in the exhaust gas. The effect of the polymeric dispersant on the acid neutralization performance was also studied. The formation of clear, thin and resilient shells surrounding sulfuric acid droplets upon reaction with some MCLs was noticed to be a detrimental aspect towards their acid neutralization performance and more importantly, due to the formation of potential precursors for cylinder liner engine deposits. Finally it is shown a modification of the capillary videomicroscopy technique that allowed long-term monitoring of the fate of microscopic particles while reacting or dissolving under flow, by suspending them using a balance between buoyancy and drag force from creep flow. / acase@tulane.edu

The spectral analysis techniques afforded us from the field of physics has enabled us to explore the spectral signatures of trace contaminants and degradation products in used or in service engine oil through atomic and molecular spectroscopy. Here we have examined the need to address proper preparation of calibrating samples for infrared spectroscopy analysis by inducing emulsification and have evaluated multiple procedures for proper emulsification of samples with the intent to help establish the protocols that are not explicitly set forth in the ASTM International standard. We have also explored the use of Fourier-transform infrared spectroscopy techniques to examine the suppression of the O–H stretching mode of water due to the influence of ethylene glycol, which may help in the quantification of water when both are present in oil. This was done in conjunction with exploring alternative methods for direct and indirect measurement of the glycol contamination by use of UV/Vis spectroscopy, Raman, and laser-induced breakdown spectroscopy. An exploration of FT-IR and UV/Vis data on the oxidation of oil by means of ANOVA calculations has led to the reporting of highly significant differences in the data of differing oxidation times and in regions of the spectrum not known to have been previously reported.

Thermal oil oxidation is an important reason for the engine oil degradation in trucks. Having a comprehensive model that includes all the influential factors while it is feasible for being implemented in the ECUs, was aimed for this work. Therefore, the chemical investigating of the problem leaded to propose a first kinetic model and its thermal analysis caused modelling the oil thermal behaviour. The latter was developed for four compartments: Bearings, turbocharger, piston cooling and oil sump in the oil path through the lubrication system, because the highest oil temperature happens due to friction, combustion of fuels and exhaust gas transportation. Independency from the design parameters of the compartments and simplicity of models for the ECU implementation caused to investigate two various modelling hybrid approach: physical modelling and control theory approach. The first one was done for the bearings and piston cooling, and showed a high level of complexity leading to switch to the second approach. The latter was applied for all compartments while it satisfied requested requirements. To adjust and evaluate the models, an experimental campaign was devoted to acquiring the needed parameters with consideration of the project budget. Also using the previous simulation and experimental efforts at the company provided a possibility to develop flow rate sub-models used in the thermal modelling. The proposed model for all compartments, well predicted the oil thermal behaviour for both stationary and dynamic operating conditions. A comparison between the experimental data for the oil in the oil sump and turbo charger was done to show the reliability of the related models in both stationary and transient statuses. For the bearings, the simulation data for stationary condition were applied as a reference. The modelled oil temperature after piston cooling was compared to a set of experimental data that presented the probable temperature in some conditions close to stationary operating points.

Laser-induced breakdown spectroscopy (LIBS) is a technique that allows quantitative and qualitative analysis of many materials. In this study, the LIBS analysis options for strontium mixture powders is expanded by increasing the number of usable strontium atomic transitions to avoid incorrect results due to spectral congestion or high strontium concentrations. The research employs double-sided tape affixed to a glass slide to hold the sample where the powder is poured onto one surface of the tape and excess dust that has not adhered is removed. This method minimizes the sample quantity needed and keeps the sample on the slide during experimentation, which also reduces costs. Herein, LIBS was used to detect and quantify the level of metal concentrations in used engine oil samples to provide valuable information about the composition of the selected material in a liquid sample. Data were obtained using multivariate analysis to develop calibration curves using LIBS spectra, which was employed for the quantification of the elements Al, Ca, Fe, Mg, and Mn. The relationship between the peak intensity of the metals in new engine oil samples and the metal concentrations in used engine oil samples were analyzed to minimize the matrix effect and the interference of element lines after which the atomic emission observed in LIBS spectra of used engine oil and new engine oil were compared. C2 molecular band emissions were also used to determine the degree of the engine oil degradation. Next, calibration models were developed for samples with high species concentrations. A partial least squares regression model was developed for calibration models to overcome matrix effect problems of some lines of each metal. This research successfully used the LIBS technique to determine the degree of engine oil degradation. This study established that used engine oil analysis using the LIBS technique can be utilized to maintain engines in good condition and to prevent engine failure. This paper presents the key findings and conclusions regarding the application of LIBS. Finally, although this technique shows many benefits and reliable results, challenges remain in terms of matrix effects, spectral pre-processing, model calibration, and instrumentation.

Superfícies anisotrópicas lisas e rugosas foram usadas para avaliar o efeito da rugosidade e da direção de acabamento na formação de MoS2 a partir de MoDTC em ensaios tribologicos lubrificados com óleos de motor completamente formulados. Igualmente foi avaliada a resposta de atrito de lubrificantes de motor usados em carros de passageiros e em testes de dinamômetro abastecidos com etanol (E100) e gasolina (E22). Encontrou-se que tanto a direção de acabamento quanto a rugosidade foram fundamentais na reação MoDTC - MoS2. A direção de acabamento influenciou na medida que carregamentos tangenciais geram respostas diferentes nos ensaios quando são realizados paralelos e perpendiculares às linhas de acabamento, dado que para os últimos apresenta-se maior deformação plástica das asperezas, o qual favorece a obtenção de superfícies livres de óxidos, que tem sido indicada como uma condição necessário para que aconteça a reação MoDTC - MoS2. Por esta razão os valores de coeficiente de atrito próprios da formação de MoS2 foram obtidos somente nas superfícies rugosas ensaiadas perpendiculares às marcas de acabamento. Para superfícies com valores de índice de plasticidade superiores a 1 e nos quais não são formados filmes com boas capacidades redutoras de atrito, como é o caso de ensaios realizados com óleos base (livres de aditivos), o coeficiente de atrito não depende da rugosidade e da direção de acabamento. Nos ensaios lubrificados com óleos usado, encontraram-se valores de coeficiente de atrito similares aos obtidos nas condições de lubrificação com óleo livres de aditivos, devido provavelmente à redução do MoDTC no lubrificante como tem sido identificado por diferentes autores. Quando foram comparados os óleos usados contaminados com etanol com os óleos usados contaminados com gasolina, encontrou-se maior oxidação nestes últimos. Mesmo que estas diferenças de oxidação dos óleos não significaram diferenças em termos de atrito, estas podem ser importantes na medida em que óleos mais oxidados podem favorecer o desgaste oxidativo. / Smooth and rough anisotropic surfaces were used to evaluate the influence of surface roughnesss and lay direction on the in-situ formation of MoS2 from MoDTC in tribological tests. Also, this work evaluated the friction response of engine lubricants which were used in passenger cars and dynamometer tests fueled both with ethanol (E100) and gasoline (E22). It was found that both the lay direction as the surface roughness were critical for the MoDTC -MoS2 reaction. The lay direction influence due to tangential loads generate different responses when tests were conducted along and across the lay, since the latter showed higher asperities plastic deformation , which favors free oxides surfaces, which has been indicated as a condition for the sequence by MoDTC formed MoS2. For this reason the friction coefficient values related to MoS2 were obtained only for tests conducted on rough surfaces and across the lay. For surfaces with plasticity index values greater than 1 and which are not formed films with good friction-reducing capabilities, such as the tests lubricated with base oil (free aditives), the friction coefficient does not depends on the surface roughness and lay direction. For the tests conducted with used engine oils, the friction coefficient values were similar to those obtained on tests lubricated with free additives oils, this could be related by MoDTC depletion in the lubricants as have been identified by different authors. Comparing the used oils contaminated with ethanol with the used oils contaminated with gasoline, higher oxidation was founded in the latter. Even if these differences in oil oxidation not meant differences friction, these may be important as more oxidesed oils can promote oxidative wear.

Requirements of high performing engine oil are today necessary since the development of new machinery with modern standardsis a cutting edge technology demanding highly optimized components. One way of increasing the lubricating properties of engineoil is through the addition of antioxidants. Antioxidants included in lubricants have a number of functions, one being buffering theinorganic acids sulphuric acid and nitric acid.A novel method expected to lower the hydrogen ion concentration in acidified engine oil was evaluated in this thesis. Thecapability of four different types of cation exchangers to serve as complements for buffering additives in heavy vehicle engineswas assessed. Two cation exchangers were weak and two were strong. The analysis techniques used to evaluate what effect thecation exchangers have on engine oil were standard test method ASTM D4739, for measurements of the total base number (TBN),and inductively coupled plasma – atomic emission spectroscopy (ICP-AES). With ASTM D4739 it was found that weak cationexchangers give positive results with respect to the ability to decrease the hydrogen ion concentration in acidified engine oil.However, after begin subjected to strong cation exchangers, ASTM D4739 indicated that the hydrogen ion concentration in theacidified engine oil remains the same or increases.With additional literature studies of a variety of cation exchangers currently on the market, further optimization of the cationexchanging material could likely be achieved. In addition, the preparation method used during the evaluation of the cationexchangers should be optimized to give more reliable results.