Investigation of oxidation of a mineral and a synthetic engine oil

Recycling of Waste Engine Oils Using a New Washing Agent

“…Oxidation of engine oil at low temperatures leads to alkylhydroperoxides ROOH, dialkylperoxides ROOR, alcohols ROH, aldehydes RCHO and ketones RR′C=O. In addition, cleavage of a dihydroperoxide leads to diketones RCO(CH 2 ) x COR′, ketoaldehydes RCO(CH 2 ) x CHO, and hydroxyketones RCH(OH)-(CH 2 ) x COR′ [53]. At high temperatures (>120 °C ) the engine oil oxidation process can be divided into a primary and a secondary oxidation phase.…”

“…The secondary oxidation phase happens at higher temperatures where the viscosity of the bulk medium increases as a result of the polycondensation of the difunctional oxygenated products formed in the primary oxidation phase. Further polycondensation and polymerization reactions of these high molecular weight intermediates lead to form sludge [53]. Reaction oxidation compounds in oil samples determined qualitatively by obtaining their IR spectra in a Fourier Transform Infrared Spectrometer (Thermo Scientific, Thermo Mattson Nicolet 300-FTIR).…”

Colloidal Stability of Metal Nanoparticles in Engine Oil under Thermal and Mechanical Load

“…The last influencing parameter on the high stability of thermally and mechanically loaded nanoparticles is a carbon layer, which is observed for laserbased nanoparticle synthesis in organic liquids [48,54]. The nanoparticles can be coated in situ by the oil's degradation products which emerge from oxidation and heat [47]. This degradation can also occur during the laser ablation process due to the high intensity of the laser beam [55].…”

“…3 d). Consequently, during the first hour of circulation, the engine oil appears to degrade more rapidly by oxidation and heat [47] under formation of UV-absorbing species. The absorbance increase of gold nanoparticles in engine oil is accompanied by a damping of the SPR peak intensity and can emerge from carbon coverage of nanoparticles [48] or by screening effects of the oil degradation products.…”

Proposal of an FTIR Methodology to Monitor Oxidation Level in Used Engine Oils: Effects of Thermal Degradation and Fuel Dilution

“…Engine oils are probably more susceptible to oxidation than in other lubricant applications, considering the high oil temperatures reached in the piston area and resulting in the called "thin film oxidation" 15 , causing that CNG oils have a higher degradation rate than in diesel engines, as it has been observed in previous studies [1][2]16 . Oxidation effect due to oil temperature leads to important changes in the oil effectiveness as a lubricant such as: increasing the acidity of the oil 17 and increasing the viscosity 18 , among other changes in properties. Consequently the lubricant becomes more aggressive toward metal surfaces, especially those non-ferrous, and modifies its ability to form a lubrication film, causing higher engine wear rate.…”