I would leave the oil in a seperate vial and draw the prop and then the oil, or whatever. I would take at least a 1:1 ratio to begin with. If that doesn't do it add a little more.
Also, for me, the pain became much less severe when I injected in the glutes only and used a 1&1/2 pin. Get it deeper in the muscle. 1 inch pin put me in a foul mood!