The available literature indicates that heating motor oil and similar lubricants typically results in a decrease in viscosity rather than an increase, though extreme oxidation over time can lead to sludge with higher molecular weight and increased viscosity.
Oxidation is considered to be one of the main causes resulting in reduced performance and increased engine oil consumption. The oil always circulates and is in contact with the air, as well as with the products of incomplete and complete combustion of fuel. The oxidation process is intense, and lubricants are susceptible to oxidation due to high temperature and the presence of metal parts, as well as their wear products acting as oxidation catalysts, neutralizing acids with alkaline additives, the dispersion of detergents deteriorates and the service life of engine oil is shortened. Acid formation is controlled by the acid number measured by potentiometric or colorimetric titration. Carbon deposits accumulate in the grooves around the piston rings, causing them to burn out. As a result, the mobility of the rings deteriorates and sufficient compression is not provided, which leads to a decrease in engine power, wear of piston groups and increased engine oil consumption. The presence of varnish on the walls of the parts leads to a decrease in heat dissipation, strength decreases and the oil film on the cylinder walls is broken. The sludge causes an increase in viscosity due to an increase in molecular weight as a result of oxidized molecules under the influence of high temperature. The catalysts are the metal surfaces of the parts. When heated, the oil comes into contact with them, and the speed of the process increases dramatically, resulting in the formation of solid oxidatio
The environmental concern about waste generation and the gradual decrease of oil reserves has led the way to finding new waste materials that may partially replace the bitumens used in the road paving industry. Used motor oil from vehicles is a waste product that could answer that demand, but it can also drastically reduce the viscosity, increasing the asphalt mixture’s rutting potential. Therefore, polymer modification should be used in order to avoid compromising the required performance of asphalt mixtures when higher amounts of waste motor oil are used. Thus, this study was aimed at assessing the performance of an asphalt binder/mixture obtained by replacing part of a paving grade bitumen (35/50) with 10% waste motor oil and 5% styrene-butadiene-styrene (SBS) as an elastomer modifier. A comparison was also made with the results of a previous study using a blend of bio-oil from fast pyrolysis and ground tire rubber modifier as a partial substitute for usual PG64-22 bitumen. The asphalt binders were tested by means of Fourier infrared spectra and dynamic shear rheology, namely by assessing their continuous high-performance grade. Later, the water sensitivity, fatigue cracking resistance, dynamic modulus and rut resistance performance of the resulting asphalt mixtures was evaluated. It was concluded that the new binder studied in this work improves the asphalt mixture’s performance, making it an excellent solution for paving works.
The heating of oil and oil products is widely used to reduce energy losses during transportation. An approach is developed to determine the effective length of the heat exchanger and the temperature of the cold coolant (oil) at its outlet in the case of a strong dependence of oil viscosity on temperature. Oil from the Uzen field (Kazakhstan) is considered as a heated coolant, and water is considered as a heating component. The method of the log–mean temperature difference, modified for the case of variable viscosity, and the methods of computational fluid dynamics (CFD) are used for calculations. The results of the numerical calculations are compared with the data obtained on the basis of a theoretical approach at a constant viscosity. When using a theoretical approach with a constant or variable viscosity, the heat transfer coefficients to cold and hot coolants are found using criterion dependencies. The Reynolds-averaged Navier–Stokes (RANS) and a turbulence model that takes into account the laminar–turbulent transition are applied. In the case of variable oil viscosity, a transition from the laminar flow regime to the turbulent one is manifested, which has a significant effect on the effective length of the heat exchanger. The obtained results of the CFD calculations are of interest for the design of heat exchangers of a new type, for example, helicoid ones.
Effect of oil temperature and viscosity on the ring gear orbit in the internal gear motor and pump is analyzed in this study. The mobility method is used to calculate the ring gear orbit. The mathematical model of oil viscosity and temperature is then integrated into the mobility method. The simulation results point out that the oil temperature and viscosity have great effect on the eccentricity, position angle and minimum oil film thickness. The metal - to - metal contact phenomenon occurs if internal gear motor and pump operates under high values of oil temperature or low values of oil viscosity conditions.
substantially decreased in viscosity (Figure 10). Overall, there was an apparent decrease in viscosity of approximately … this effect was enhanced for increases in applied amplitude and increases in arc length from the nozzle … water, motor oil, and crude oil. The water had a specific gravity of 1 g./cc., the motor oil 0.879 g
This paper presents a systematic review of electrically enhanced oil recovery (EEOR), focusing on the critical gap between its promising laboratory performance and the slow pace of industrial deployment. First, the current state of EEOR applications is reviewed. Although extensive laboratory research has confirmed its technical feasibility, field applications remain mostly confined to pilot-scale projects, particularly in heavy oil and oil sands reservoirs. These trials demonstrate EEOR's potential to outperform conventional steam flooding in terms of recovery efficiency and energy utilization, but they also expose significant challengessuch as low reliability of downhole hardware (with failure rates reaching up to 75% in some projects), geomechanical instability, and operational difficultieshighlighting the technological gap between experimental success and large-scale reliability. Second, the review elucidates the fundamental mechanisms underlying EEOR. As a multiphysics coupled process, EEOR is governed by electrodynamic, electrothermal, and electrochemical effects. Key mechanisms include: electrodynamic effects (electroosmosis and electrophoresis), which provide nonpressure-driven flow forces; electrothermal effects (primarily Joule heating), which reduce heavy oil viscosity; and electrochemical effects (electrowetting and redox reactions), which alter wettability and enable in situ upgrading. A key insight is the inherent interplayboth antagonistic and synergisticamong these mechanisms, with reservoir water salinity serving as the central regulatory factor. The review further discusses emerging technologies, such as electromagnetic-assisted composite flooding and plasma pulse stimulation, emphasizing their potential for synergistic enhancement through multiphysics coupling. Third, economic and operational constraints are critically assessed. Although EEOR may offer energy cost advantages under specific conditions, its commercial viability is hindered by high electricity prices, substantial capital investment, and operational risks arising from equipment failures. Finally, this review outlines a forward-looking perspective. The advancement of EEOR depends on shifting the research focus from mechanism validation to resolving engineering bottlenecks. Future efforts should prioritize the development of highly reliable, long-lifetime downhole electrode and cable systems, the construction of quantitative models capable of predicting coupled multifield effects, and the integration of artificial intelligence for process optimization. Such an engineering-driven approach is essential for transforming EEOR from a promising laboratory concept into a practical, field-deployable technology.
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