Wax naturally present in crude oil is partially removed during refining.  The “Wax Appearance Point” is the temperature at which the wax will begin to separate from the oil, potentially clogging  filters and causing  insufficient fuel delivery.  This test determines the wax appearance point in turbine engine fuels, diesel fuels, burner fuels and other distillate fuels,      

 

The sample is dried, heated if necessary and then cooled slowly while being carefully observed.  The temperature at which wax crystals are first observed is reported.