I have never mixed oils in a larger vial and drawn from the mixture. I am too paranoid that I would not be getting the right percentage of each, like you guys said.

Even with sust., you inject the whole vial, so even if there is any separation, it does not matter. Not the case with drawing from a large vial though - and do the heaver esters go to the bottom and the lighter ones to the top? I don't know enough about chemistry to answer, but would be interested in the answer to this one.