The feasibility of oil identification by nonfragmenting field ionization multiscanning mass spectrometry has been demonstrated. A system consisting of a multipoint field ionization source, ion optics elements, E x B velocity filter, detector and image intensifying fluorescent screen for spectrometer tuning and a 4096-channel analyzer is described in detail. Preparation of oil samples by vacuum distillation and chemical derivatization is also described. A statistical model for the analysis of spectrometer data is derived and applied to selected peaks from spectra consisting of the integration of more than 1000 scans of fuel oil samples in the mass range 190 M 380 amu. Included are discussions of spectrometer noise and stability, systematic errors, and the feasibility of computer data handling.