ABSTRACT Advanced geochemical technologies (AGT) were applied to 12 oils from pre-salt formations (pre-salt oils) from the Santos Basin and compared to four post-salt reservoired oils. Three primary methods were used to categorize the oils: (1) diamondoid methods, that is, quantitative diamondoid analysis (QDA) and quantitative extended diamondoid analysis (QEDA); (2) biomarker analyses using gas chromatography–mass spectrometry–mass spectrometry (GCMSMS); and (3) compound specific isotope analysis of alkanes and hopanes plus tricyclic terpanes (CSIA-A and CSIA-Bh/CSIA-TT, respectively). Each method either provided new information or reinforced interpretations derived from other methods diminishing uncertainties in the overall interpretations. GCMSMS data suggested the preliminary source relationships for charges of early-to-middle oil-window maturity based on biomarker correlations. Those suggestions from GCMSMS data were either bolstered or more finely discriminated by the CSIA data. Data from diamondoid analyses gave insight into components that could not be described by biomarkers and the CSIA methods related to post-mature oil, oil cracking, and oil mixtures. QDA showed post-mature components for some oil samples, indicative of oil-window plus post-oil-window mixtures. QEDA showed that, in addition to one predominant lacustrine source, other lacustrine sources contributed to some of the pre-salt oil accumulations. Oils taken from pre-salt reservoirs in the study include samples from the following fields: Bem-Te-Vi, Sapinhoá, Jupiter, Mero, Buzios, Tingua, Tupi, Sururu, and Carcará. Biomarker and CSIA data confirm correlative relationships among nine pre-salt oils with source rocks deposited in brackish-to-saline water lacustrine depositional environments, putatively from the upper Barremian (Itapema Formation). Among those, QDA shows the samples from Tupi (three samples), Mero (two samples), and Jupiter to be of mixed maturity, including some normal oil-window plus post-mature cracked oil. Oils from Sapinhoá, Buzios, and Sururu fields show only the normal oil-window maturity. Oils from Bem-Te-Vi and Carcará correlate to a different source proposed to be the mid-to-late Aptian-sag lacustrine hypersaline system (Barra Velha Formation), of which the Carcará oil shows a major cracked component, whereas the Bem-Te-Vi oil does not. The oil from Tingua Field appears to be the lone representative of a fresh-to-brackish water system, putatively, the lower Barremian rift system (Piçarras Formation). Four oils from post-salt reservoirs recovered from Albian carbonates from the Guaruja Formation in the southern Santos Basin show contrasting biomarker, CSIA, and diamondoid (QEDA) patterns distinguishing them from any of the pre-salt oils. Taxon-specific biomarker parameters based on GCMSMS analysis are definitive for making those distinctions, including, for example, 24- n -propylcholestanes (marine algal steranes), dinosteranes concentrations (dinoflagellate steranes), and other A-ring methyl steranes and 24-norcholestanes (putatively diatom related). One of the highly cracked post-salt oils is an example of oil co-sourcing, showing features of both lacustrine and marine components in the biomarker and diamondoid parameters.