Abstract: A diesel fuel composition which essentially comprises only paraffins, and wherein the proportion of the content of paraffins of 15 or fewer carbons is made not less than 28% by volume and the proportion of normal paraffins of 18 or more carbons is made not more than 11% by volume. The diesel fuel composition has improved rubber swellability.

Abstract: A diesel fuel composition which essentially comprises only paraffins, and which is characterised in that 1) the normal paraffins with 18 or fewer carbons constitute not less than 12% by mass, and 2) the proportion of the total peak area of the peak group at chemical shifts of 1.45 to 2.25 ppm relative to the total peak area of the peak group at chemical shifts of 1.00 to 1.45 ppm is less than 6.5% in proton nuclear magnetic resonance (1H-NMR) spectra, and which has an oxidation index OI of less than 1.10. OI is represented by the equation OI=0.247X?0.001Y?0.053, wherein X is the proportion (%) of the total peak area of the peak group at chemical shifts of 1.45 to 2.25 ppm relative to the total peak area of the peak group at chemical shifts of 1.00 to 1.45 ppm in proton nuclear magnetic resonance (1H-NMR) spectra; and Y is the content (mass %) of normal paraffins with 18 or fewer carbons.