The stability of diesel fuel is a complex issue, and the blend of fossil fuels with biodiesel added new concerns to the problem. Many standard test methods exist to evaluate the tendency of thermal and oxidative degradation. These procedures perform specific stressing conditions to accelerate oxidation and rate fuels on a relative stability scale. In this work, 18 diesel fuel samples containing 8% v/v biodiesel collected in representative Brazilian gas stations spread across different states of the country were submitted to four standard stability tests and analyzed with mid-infrared (IR) spectroscopy. The stability studies were carried out according to the ASTM standard procedures D4625, D6468, and D7545 and the CEN standard EN15751. The data generated were evaluated with the chemometric tool parallel factor analysis (PARAFAC), which decomposes the data array in few independent factors that explain the main sources of variation and allow the evaluation of the differences in the physical and chemical modifications caused by the stress conditions of the stability tests despite the differences in the characteristics of the fuels. PARAFAC decomposed the spectral data unveiling different degradation patterns for each stability test, except for the D6468 test for which the alterations in the IR spectra were negligible or masked by the variability among samples. EN15751 promoted the most extensive degradation, generating oxidized products and the loss of volatile matter. On the other hand, D7545 promoted intense oxidation, whereas D4625 caused, apparently, only volatilization of lighter hydrocarbons.