Abstract: A method and apparatus for determining the presence or absence of a pour point depressant additive in hydrocarbon liquids includes cooling a sample of the liquid at a predetermined cooling rate from a temperature substantially above the cloud point temperature of the sample liquid to a temperature substantially below the cloud point temperature of the sample liquid. The points on the cooling rate curve for the sample at which a deflection of the curve begins and ends is determined and the time interval between the beginning and ending points of the cooling rate curve is computed. This computed time interval between the beginning and ending points is compared to a reference time interval such that if the reference time interval is less than or greater than the computed time interval between the beginning and ending points on the cooling curve, the presence or absence, respectively, of a pour point depressant additive in the sample is determined.