AbstractA lubricating oil base stock, Inter Neutral type, boiling range 282–562°C, was fractionated into three boiling ranges of 282–456, 456–492, and 492–562°C. The waxes were isolated from the parent base stock and its fractions by solvent dewaxing. Hydrocarbon‐type constituents, i.e., saturates, naphthenic aromatics, and polar aromatics, were separated by elution chromatography and were characterised for their physical properties. The viscosity–temperature behaviour of the base stock sample and its various fractions and components, i.e., dewaxed oil, extracted waxes, saturates, naphthenic aromatics, and polar aromatics, was determined and correlated with the composition. It was found that the concentration, nature, and type of hydrocarbon components present greatly influenced the physical properties as well as the viscosity–temperature behaviour. The average chain lengths of the waxes obtained by 1H NMR match well with those determined by gas chromatography. Copyright © 2006 John Wiley & Sons, Ltd.