Influence of chemical structures on low-temperature rheology, oxidative stability, and physical properties of group II and III base oils

The effect of base oil composition on lubricant properties has been studied to better understand low-temperature rheology, oxidative stability, and other physical properties. A simple approach has been adopted using low-temperature rheology to develop a multi-linear regression model to estimate Brookfield viscosity. Six base oils from API groups II and III were studied using different nuclear magnetic resonance spectroscopy methods. One method involved determination of average structural parameters from quantitative ¹³C NMR data, while the other method involved measurement of spin-lattice relaxation times at variable temperatures. The structural information obtained from these two methods was used to develop meaningful correlations for low-temperature, oxidative, and physical properties of these base oils. The study suggests that a deeper knowledge of chemical composition will help in selecting base oils to meet future product specifications.