Question about using Neem oil as a drench

[zygostates]

Hello,
I am an inside/under lights orchid grower. In Fall, I move the orchids inside in the basement. Despite preventative spraying for a month before moving all of the orchid inside, I have had a mealy bug and red spider mite infestation. I would like to use Neem oil in order to avoid commercial insecticides off gassing in my basement. I have mealy bugs in the media in some of my plants. I was wondering if I could use neem oil not only as a a topical application but as a drench application as well. Has anyone done this before with success? What would be the application ratio?...is it different from the topical ratio? Also..Is the DyNaGro Neem Oil different from the Cold Pressed Neem Oil that is used for skin applications?
Thank you
Glenn