Based on the study of a large number of Western and Eastern Siberia oils, it was shown that adamantanes can be used as a means of correlation in oils of different genotypes and ages. Based on the relative distribution of mono-, di-, and trialkyl-substituted C11–C13 adamantanes marine and terristerial oils and Cenozoic and Proterozoic oils were distinguished. This approach could be used when there are no generally recognized biomarker hydrocarbons or indicators based on them are uninformative. We found that Jurassic and Cretaceous oils of Kalmykia can be distinguished by the distribution of methyl- and dimethyldiamantanes. It was concluded that the distributions of alkyl substituted diamantanes could also be applied for the differentiation of oils of different ages.