Destruction of an oil alkane (paraffin) fraction by oil-destroying microorganisms was studied. The destruction rate was clearly dependent on the chain length. An increase in the number of alkanes with shorter chain lengths was indicative of the destruction of supramolecular oil structures and the oxidation of higher-molecular-mass compounds. Species and strain features of alkane destruction were found. Principal components analysis was used to show that Rhodococcus erythropolis and Acinetobacter guillouiae demonstrated different behaviors in the decomposition of alkanes. The oil destroyers were not capable of destroying all oil fractions with equal efficiencies. Based on previous studies, it could be confirmed that R erythropolis preferred the alkane fraction; A. guillouiae, the aromatic fraction.