Solid phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS) of the headspace composition of two sunflower oil samples was carried out; both samples were taken from the same original oil, stored for a prolonged time (112 months) in closed containers at room temperature under different air/oil volume ratios. Great differences in the headspace compositions of both samples were found due to the different oxidation levels reached. One of the most significant findings is that both contain monocyclic and light polycyclic aromatic hydrocarbons, the proportions of which are in line with the oxidation level of the sample. The determination of polycyclic aromatic compounds in the oil liquid matrix of both oil samples, carried out by means of a classical scheme of isolation, cleanup, separation, and quantification, showed that the concentrations of these compounds in the oil liquid phase also follow the oxidation degree reached by each sample, proving that this oxidation process at room temperature leads to the formation of these compounds.