The cloud point represents the temperature at which wax or paraffin begins to precipitate from a hydrocarbon solution. Conventional American Soc. for Testing & Materials (ASTM) procedures for cloud-point determination are not applicable to dark crude oils and also do not account for potential subcooling of the wax. A review of possible methods and testing with several crude oils indicate that a reliable method consists of determining the temperature at which wax deposits begin to form on a cooled surface exposed to warm, flowing oil. A concurrent thermal analysis of the waxy hydrocarbon can indicate the presence of possible multiple wax-precipitation temperature regions in the solution.