Oil and water is not the problem. The molecule of Hcg is fairly fragile. Don't shake it up when you put the water, Bacterial static or saline, into the vial. The correct way to to just roll the vial around. Use a small gauge needle and inject IM. Some people say it doesn't matter if it's IM or SubQ but the people that make the stuff say do IM. It's up to you. I always do IM with a 25 gauge 1.5" needle.