don't believe the 

you will undoubtedly at some point read in some machine manual how you must USE THE MANUFACTURES FOG FLUID OR IT WILL VOID THE WARRANTY OR CAUSE MASSIVE WIDE SPREAD DISEASE IF YOU DONT (NOT THAT BAD).  
THERE IS SOME MANUFACTURES THAT CLAIM TO "CALIBRATE" THEIR FOG MACHINES TO USE THEIR FLUID, while some of this may be true to a degree, the fluid composition makes   but for the most part the heaters are set to a range tha