The molecular composition of the oil-based lubricating-cooling liquid SP-4 has been studied by chromato-mass-spectrometry. The regular isoprenoids 2,6,10,14-tetramethyl pentadecane and 2,6,10,14-tetramethyl hexadecane have been detected in the liquid. It is suggested that in due course isoprenoids of the p-like structure will be detected in the high-boiling fractions of paraffinic crude oils.