aniline point

The temperature at which the two phases separate out is recorded as aniline point.

The lower the aniline point, the greater is the content of aromatic compounds in the oil as obviously a lower temperature is needed to ensure miscibility.

The aniline point serves as a reasonable proxy of the aromatic content as petrochemical oils largely consist of saturated hydrocarbons (i.e. alkanes, paraffins) or unsaturated compounds (mostly aromatics) only.