....I take it your wanting to coat the mold with something....if so a mold release will work. Also , a thin coat of petroleum jelly on the mold will prevent any resin from sticking to the metal/steel mold. Another possibility would be a dusting of Talcum powder, especially if there are any under cuts or other complex shapes.
Stoner would probably work, I haven't tried it myself but most release agents work the same way for the most part. If you're unsure you can test it with something similar to what you're casting with that you're not worried about messing up if it doesn't work. Since you're using a metal mold, you have to have something in between the mold and resin just to be able to get the resin casting out so most anything that the resin won't stick to will work.