| Abstract: | The ageing characteristics of two competing lubricants, monograde and multigrade crankaase oils, have been studied. A combination of oil acidity, deposit formation and infra-red spectroscopy were used to follow the ageing of the lubricating oils. Both oils showed a similar pattern of ageing. However, the monograde oil, showed a higher tendency to form carbonyl compounds, but the multigrade oils formed more active carbonyl compounds, which polymerized rapidly to form deposits. Consequently, the multigrade oil aged faster than the monograde oil. |
