You still have to start with an oil that's compatible with the plastic. I use regular worm oil to make scented oil using anise essential oil. I've got a bottle of anise essential oil that I have had for ten years and I still have 1/2 of the 1 ounce bottle. I mix about 1/4 ounce with a cup of worm oil and pour some into a bottle that has an eye dropper. 1 drop goes into a bag of baits when I have it ready to send. Depending on the size of the zip lock the baits are in, between 2 and 4 drops of regular unscented worm oil goes in the baits too. ONE drop of the anise scented oil. Kind of get where I'm headed here?
An 8 ounce bottle of worm oil and a one ounce bottle of essential anise oil will last a looooooooong time. Stop and think about the economics here.....worm oil is about the least expensive component of the soft bait making game when one considers just how far the stuff goes and if you're making scented oil you'll be an old old man before you use up that one ounce bottle of anise essential.
Using mineral oil or some other oil might end up gelling in the baits or may contain a scent that is entirely offensive to fish. Worm oil I scent free and does not have any ill glitches because of additives.