In general, oils and soaps will not work well in Ultra Low Volume equipment. Because these products smother the insect, larger volumes of water are needed for these products to work properly.
Oils and soaps may be used in the Coldfogger, but higher applications volumes are needed than when using with a low volume method.
There is research to suggest that oils and soaps may have a synergistic effect when mixed with other contact insecticides as the oils and soaps work on the insect's chitin. It is theorized that these products weaken a primary line of defense for the insect, allowing other contact products to work more effectively.