Do you not know of the water method?

Fill the vials with water and then dump them out. Leave a few drops of water in. Take your pin and work it around the vial, scraping at the oil residue.

Oil and water don't mix so all the oil will coagulate together on the pin. You can then pull it out and spread it on the paper or do BTs or however you smoke it. You can get all the oil off, even on the threads. Your vials should get to be crystal clear, if you haven't burned them by now.