One particularly noteworthy feature in the DSC diagram of crude oil is the Individual Wax Appearance Temperature (WAT). The diagram displays both heating (red) and cooling (blue) curves of a crude oil sample within a temperature range of -20°C to 140°C. As the oil is heated, solid components transition into a liquid state, causing a reduction in viscosity. This melting process manifests as a broad peak on the diagram, reflecting the simultaneous melting of various compounds across a specific temperature range.

During cooling, the crystallization process occurs, marked by an exothermic effect. Given that oils contain heavy organic compounds that are not fully liquid at room temperature, a wax-like component is always present. While heating leads to a challenging-to-evaluate broad melting peak, cooling reveals a distinct and sharp onset of crystallization. This onset temperature serves as a defining characteristic, allowing for the characterization of individual crude oil compositions. Leveraging this effect during cooling in DSC can prove instrumental in quality control processes.