Essential oil frequencies are too high for the standard Healing Preset to make work in the generator as they are and would further divide down the frequency to a sub-harmonic of the frequency - but without any math settings designed to push the frequencies back up where they need to be.
It would be better to choose one of the Essential Oil Presets to run all of the healing programs as through the use of the harmonics specifically designed into the wave settings, these will hit the true frequency of the Essential oil.
Please provide further information about the example you are describing of a program for back pain containing oil frequencies. The specific name of the program - or Preset - would be helpful for us to assist your understanding.
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