NMR Investigations on the Aging of Motor Oils

Aging of motor oil is characterized by diverse NMR methods to get insight into the chemical processes which occur during aging. Already one-dimensional 1H and 13C spectra reveal the relevance of chemical aging also with respect to the mechanical behavior of oils. As NMR is a quantitative analytical method, the absolute chemical changes can be observed and quantified. In addition, the spectral interpretation in terms of chemical composition is confirmed and deepened by two-dimensional 1H–1H, 1H–13C, and 1H–15N correlation spectra, as well as diffusion and relaxation experiments. The different NMR results are discussed and interpreted to obtain a thorough picture about aging processes of motor oils.