Pour point is the lowest temperature at which a lubricant will flow under specified conditions. Most lubricant suppliers give the pour point of their oils so that the user can determine if it can be pumped and would be fluid in low temperature applications.

The pour point increases with viscosity. For example, an ISOVG 46 mineral oil might have a pour point of -39 degree C, whereas an ISOVG 460 would have a pour point of -15 degree C. For mineral oils, the increase in viscosity as temperature is reduced, is due to gelling of the oil by the precipitation of crystalline wax.

It should be noted that one advantage of many synthetic oils is their very low pour points because of the absence of wax. Pour point depressants for mineral oils are additives which lower the pour point by interfering with wax crystallization.

Pour point is measured by ASTM D 97, which describes the procedure for cooling an oil until it will not pour out of a vessel. Cloud point is defined as the temperature at which a wax cloud first appears on cooling mineral oil under specified conditions.