Data processing techniques have been developed for the manipulation and enhancement of spectroscopic data. They have been applied to the infrared spectra of degraded base oils and lubricants to provide information on oxidation processes and additive depletion. Samples have been acquired from oils that have been subjected to laboratory scale oxidation and from lubricants during standard engine tests. Results are evaluated in terms of chemical species that are lost and formed during oxidative degradation.Presented at the 40th Annual Meeting in Las Vegas, Nevada May 6–9, 1985