Oil pour point is the lowest temperature (in oC or oF) at which oil still behaves as a fluid. It is determined following the standard method ASTM D97, “Standard Test Method for Pour Point of Crude Oils”. The sample is placed in a tube closed with a rubber stopper and a thermometer in it. The tube is cooled inside a cooling bath to allow the formation of paraffin wax crystals. At about 9°C above the expected pour point, and for every subsequent 3°C, the test jar is removed and tilted to check for surface movement. When the specimen does not flow when tilted, the jar is held horizontally for 5 sec. If it does not flow, 3 °C is added to the corresponding temperature and the result is the pour point temperature.
Wax content of an oil is determined using the SETARAM LABSYS evo Differential Scanning Calorimetry (DSC system). The measurement is based on the amount of heat, released during phase transition on the melting point of heavy paraffins of the sample.