Evaluation of Oxidative and Thermal Stability of Base Oil for Automotive Application

Synergistic and antagonistic effects have been observed with the four sulfur-, phosphorus- and heavy metal-free antioxidants, hindered bis-phenol (HP), octylated diphenylamine (ODPA), octylated phenyl-alpha-naphthylamine (OPANA) and tolutriazole derivative (TZ), on the oxidation stability, thermal and physicochemical properties of dioctyl sebacate base oil. The oxidation stability was evaluated using a rotating bomb oxidation tester (RBOT). The results from isothermal and catalytic oxidation tests suggested that octylated diphenylamine has an antagonistic effect on the oxidation induction time (OIT). The combination of hindered bis-phenol: octylated phenyl-alpha-naphthylamine: tolutriazole derivative exhibited the highest synergistic antioxidant activity. Furthermore, synergism was observed in terms of both oxidation and thermal stabilities through thermogravimetric analysis (TGA).The confirmation has been studied by means of electron spin resonance spectroscopy (ESR) to obtain information on the thermal oxidation mechanism of the synergistic antioxidant.

Demand for lubricating oils is increasing in the growing Brazilian economy. The use of vegetable bases in exchange of minerals can bring socio-economic and environmental benefits for Brazil. The purpose of this study is to compare the thermal and oxidative stability of vegetable oils related to the bases commonly used as lubricants. In this study, thermogravimetric analysis of castor oil, cotton oil, macauba’s almond oil, passion oil, paraffinic mineral oil, naphthenic oil (NH-140) and synthetic oil (Etro) was performed in inert and oxidative atmosphere to study the thermal and oxidative degradation of the vegetable oils related to the most common lubricants’ oils base. These oils’ oxidation stability were determined by standard procedures (ISO 6886). The use of mineral oil’s additives in these vegetable oils was tested to verify the viability of these additives to improve the oxidative stability of the vegetable oils. The castor oil and the cotton oil presented results of thermal analysis similar to the mineral and synthetic bases values. The castor oil was the only vegetable oil that showed a great oxidative stability. All other vegetable oils had their oxidative stability significantly increased by the additives.

Exploration on the synergistic effect of antioxidants for coal-to-liquid base oil: From the perspective of oxidation resistance and thermal stability

Composition and oxidation stability of SAE 15W-40 engine oils

The relationship between the structure characteristics and performances of coal-based hydrogenation isomeric (CTL) base oil and metallocene-catalyzed coal-based poly-alpha-olefin (mPAO) base oil is clarified in this paper. CTL and mPAO were compared with typical petroleum-based and natural gas-based commercial API III and IV base oils. Pressurized differential scanning calorimetry (PDSC), the rotary bomb oxidation test (RBOT), and a four-ball friction tester were used to evaluate the oxidation stability and lubrication performance of base oils under different working conditions. The sensitivity of different base oils to typical antioxidants and extreme-pressure antiwear agents was compared. In particular, the composition and structure of CTL base oil are clearly different from GTL and mineral base oil. The coal-based CTL and mPAO base oils exhibit commendable viscosity–temperature properties, coupled with low-temperature fluidity, fire safety, and minimal evaporation loss. The lubricating properties, oxidation stability, and sensitivity to extreme-pressure antiwear agents of CTL are close to those of similar base oils. However, the sensitivity of CTL to typical antioxidants is relatively poor. In addition, compared with commercial PAO base oil, mPAO has a lower isomerization degree and fewer isomerization types. The oxidation stability and sensitivity to typical antioxidants of mPAO base oil are comparable with those of commercial PAO base oil, while its lubrication performance and sensitivity to typical extreme-pressure antiwear agents are significantly better than those of commercial PAO base oil.

Waste engine oil one of the most abundant wastes in Malaysia, and through the reutilization of waste automotive engine oil helps to create a sustainable environment. The objective of this research is to develop the best formulation of lithium complex grease derived from waste automotive engine oil as base oil. The main focused parameter in this study is the different formulation ratio of base oil, thickener and co-thickener. Lithium 12-hydroxystearate is mixed with azelaic acid to produce lithium complex 12-hydroxystearate. Two different type of base oils, i.e. fresh automotive engine oil (FAO) and waste automotive engine oil (WEO) are used to formulate Li-complex grease. The grease derived from FAO is used to compare the physical properties derived from WEO. The texture of the formulation of base oil higher than 82 weight percentage was very fluid. The formulation of grease is carried out by differencing the ratio of the waste automotive engine oil, lithium complex 12-hydroxystearate and azelaic acid, which are 82:18, 80:20 and 70:30. The properties of the grease formulated is conducted through several tests, such as ASTM approach, Fourier Transform Infrared Spectroscopy (FTIR) characterization, oil separation and thermogravimetric analysis (TGA). Such interesting properties included consistency, chemical compound of the grease, oil separation and thermal stability. Based on the finding, the best formulated Li-complex grease is WG3, classified NLGI 3. The significant peak derived from FAO and WEO to observe is 1710 cm−1 as this peak indicated the oxidation stability. From the result, the intensity of carboxylic acid is weak that ranged 1709 – 1711 cm−1. Hence, this indicated the grease formulated exhibited better oxidation stability. Furthermore, the formulated grease was thermally stable as the onset temperature was 250.09 °C. In conclusion, the formulation of Li-complex from WEO can be used as an alternative source of base oil in the grease industry, due to the good properties exhibition and preserving the environment as well as the increment of fossil fuel’s demand and cost.

Along with the ever stricter economical, technical and mainly environmental regulations new types of low phosphorus, sulphur and metal containing multifunctional lubricant additives are required for formulating so-called low SAPS (Sulphated Ash, Phosphorus and Sulphur) engine oils. In the greatest volume dispersant additives, mainly polyisobuthylene-succinimide types are used in the formulation of engine oils. By structural modification of the dispersants with molybdenum and sulphur containing compounds advantageous complementary effects could be achieved along dispersant efficiency. Various modified PIB-polysuccinimides with complementary antifriction and antiwear (AF/AW), viscosity-index improver and enhanced detergent-dispersant properties were synthesized and investigated both in base oil and engine oil compositions. The detergent-dispersant and the high temperature deposit preventing effects, thermal- and oxidation stability, AF/AW properties and seal compatibility were studied in fully formulated, low SAPS engine oils with reduced zinc-dialkyl-dithiophosphate (ZnDDP) content. Based on the results it was found that by using suitable additive concentrations the conventional dispersant can be advantageously combined or replaced with these new additives to enhance the properties and to reduce the ZnDDP concentration level of the experimental engine oils.

Oxidation and low temperature stability of polymerized soybean oil-based lubricants

Oxidative and thermal stabilities of genetically modified high oleic sunflower oil

The growing interest in biobased lubricants presents a sustainable alternative to petroleum-derived base oils, with significant potential to reduce environmental pollution. Vegetable oils, known for their rapid biodegradability, offer promising prospects as base fluids in the formulation of environmentally friendly lubricants. However, their practical application is often hindered by inherent limitations such as poor oxidative and low-temperature stability. This study evaluates the thermo-oxidative performance of six biolubricant blends derived from Shea butter, palm oil, butter, and tallow oils. Using thermogravimetric analysis (TGA), the thermal and oxidative stability of each blend was assessed. Among the tested samples, the Shea butter–butter oil blend (SBBOL) exhibited the highest thermal and oxidative stability, with decomposition temperatures of approximately 560 °C and 450 °C at 90% weight loss, respectively. The tallow–Shea butter blend (TSBOL) demonstrated a thermal stability of 520 °C, while the butter–tallow blend showed enhanced oxidative resistance at 410 °C. Other blends, including palm oil–tallow (POTOL) and butter–tallow (BTOL), exhibited thermal stability values of 510 °C and 410 °C, respectively, with corresponding oxidative stabilities of 367 °C and 410 °C. The findings confirm that physical blending of biolubricants enhances their thermo-oxidative properties. The role of oxygen in accelerating degradation at elevated temperatures further underscores the need for optimized formulations to extend lubricant life and performance. This study contributes to the advancement of eco-friendly lubrication technologies through improved biolubricant formulation strategies.

The objective of the study was to develop the oil blend with improved omega-6 to omega-3 fatty acid ratio (ω-6:ω-3) with good oxidative and thermal stability. Flaxseed oil and palm olein were selected for the blending. Flaxseed oil is rich in anti-inflammatory omega-3 fatty acid (ω-3 FA)but isoxidatively very unstable. Palm olein has low omega-6 fatty acid content and high thermal and oxidative stability. Blends containing various percent (v/v) of flaxseed oil and palm olein were prepared. Oxidative and thermal stability was determined by analyzing peroxide value, acid value, smoke point, % free fatty acids, para-Anisidine and TOTOX values. Nutritive quality was confirmed by determining fatty acid composition. Nine month storage stability of the blend containing highest flaxseed oil percentage was assessed in terms of peroxide and acid value and fatty acid composition. The biological effects were studied in THP-1 cell line as the effect on cell survival, FA uptake and inflammatory markers. The data indicates that, blending improved ω-6:ω-3 ratio. Oxidative and thermal stability study, and nine month storage stability study suggested that palm olein imparted stability to the blend. Fatty acid profiles of the cells treated with these blends showed uptake of Alpha Linolenic Acid (ω-3 FA). These blends lowered inflammatory TNFα level without affecting cell survival. Thus, blending of flaxseed oil with palm olein may result in better health benefits owing to their improved nutritional and stability properties.

The present study investigates the oxidative and thermal stability of flavoured oils developed by incorporating essential oils from black pepper and ginger to coconut oil (CNO) at concentrations of 0.1 and 1.0% (CNOP-0.1, CNOP-1, CNOG-0.1, CNOG-1). The stability of oils were assessed in terms of free fatty acids, peroxide, p-anisidine, conjugated diene and triene values and compared with CNO without any additives and a positive control with synthetic antioxidant TBHQ (CNOT). It was found that the stability of CNOP-1 and CNOG-1 were comparable with CNOT at both study conditions. The possibility of flavoured oil as a table top salad oil was explored by incorporating the same in vegetable salad and was found more acceptable than the control, on sensory evaluation. The synergetic effect of essential oil as a flavour enhancer and a powerful natural antioxidant that can slow down the oxidation of fats was established in the study.

Synergistic and antagonistic effects on oxidation stability of antioxidants in a synthetic ester based oil

Relevance. The development of methods for controlling materials, products, substances and the natural environment should be completed by the validation stage. There is a well-known list of validation characteristics and recommendations for their evaluation for methods of controlling the composition of materials, products, substances and the natural environment. However, these descriptions and recommendations cannot be fully used in the case of methods for controlling the properties of materials, products, substances and the natural environment, in particular, the performance characteristics of fuels and motor oils.The purpose. Development of a procedure for validating methods for controlling the performance characteristics of fuels and motor oils and confirming the possibility of its practical implementation.Methods. The practical verification of the theoretical provisions was carried out during the validation of the method for controlling the thermal and oxidative stability of jet engine fuels under dynamic conditions. The essence of the method is to estimate the amount of deposits formed during the oxidation of fuel for jet engines under conditions of its pumping through an annular channel along a heated evaluation tube located inside the channel. Oxidation products accumulate as deposits on the surface of the evaluation tube, reducing its reflectivity, and on the filter element of the control filter, increasing the pressure drop on the control filter. Thermal and oxidative stability is monitored according to the following indicators: thermal stability index, the temperature at which deposits form, and the rate of pressure drop across the filter. The method is implemented on the basis of the DTS-4 laboratory installation.Results. Based on the specifics of the procedure and the controls used, a set of validation characteristics of methods for monitoring the operational properties of fuels and motor oils is proposed: precision and accuracy of the control method; suitability of controls; range of values of controlled quantities; sensitivity of the control method to changes in the composition of fuel (oil); robustness of the method to small changes in control parameters; comparison of the newly developed method with already known methods having a similar functional purpose; the quality of modeling of the studied chemmotological process. To increase the efficiency of validation work, it is advisable to provide an additional stage for the development of a control sample with constant, guaranteed reproducible values characterizing the performance properties of motor fuels and oils (the internal standard of the control method).Conclusion. The experience of validating the DTS-4 method shows that the developed procedure for validating methods for monitoring the performance characteristics of fuels and motor oils ensures that a sufficient amount of objective data is obtained that the new control method allows obtaining reliable information about a given operational property of the studied petroleum product.

In this study, oxidative stability of hoki and tuna oils were measured at 80°C by Differential Scanning Calorimetry (DSC) and thermogravimetric analysis (TGA) under an air atmosphere. The onset time for oxidation (to) of hoki oil occurred earlier in the TGA (222.50 min) compared to DSC (640.83 min) as the sample gained weight prior to decomposition. Conversely, the to of tuna oil could not be recorded since tuna oil was rapidly oxidized. The predicted shelf life of hoki oil for onset of oxygen uptake and subsequent decomposition at 4°C, by Arrhenius extrapolation of TGA and DSC under different isothermal treatments were 0.56 and 1.39 years, respectively. Temperature programmed decomposition of hoki and tuna oils by TGA occurred in three thermal stages, suggesting a progressive degradation of polyunsaturated fatty acids (PUFA), monounsaturated fatty acids (MUFA), and saturated fatty acids (SFA), followed by volatilization of polymerization and pyrolysis products.Practical applications: Fish oil has been marketed as dietary supplements and as an ingredient for food products. However, these products are susceptible to oxidation due to the high‐PUFA content in fish oil. Oxidative and thermal stability of fish oil are important parameters in the processing and production of fish oil and fish oil fortified food products. These data can be used by fish oil and food manufacturers to optimize processing conditions for fish oil and food products fortified with fish oil. The oxidative stability of fish oils over temperature ranges and storage times can be measured by both isothermal and non‐isothermal DSC and TGA analyses. These techniques are more rapid and provide continuous data compared to conventional shelf life studies and alternative instrumental methods. Shelf life of the fish oils can be predicted by an Arrhenius extrapolation from elevated isothermal DSC and TGA analyses.Measurement of oxidative stability of fish oils by DSC and TGA follow the Q10 law on the relationship between temperature and rate of chemical reaction. Prediction of shelf life of the fish oils is possible by an Arrhenius extrapolation from elevated isothermal DSC and TGA analyses. Differences in the thermal behavior of the fish oils were consistent with major fatty acid compositional differences.