The paper presents data on the possibility of using the proportions of concentrations of polycyclic aromatic hydrocarbons (PAH) as indicators of the pollution sources with oil hydrocarbons. Approaches are suggested to estimate the efficiency of these indicator ratios, and the efficiency of the currently used ratios is evaluated. Multivariate data analysis is applied to demonstrate how the ratios depend on the degree of transformation of the petroleum products. The data presented in the paper are utilized to more accurately determine the indicator ratios of oil-bearing samples with regard for the contamination age. © 2017, Pleiades Publishing, Ltd.