I use a two-step process to clean my olive oil bottles. First, fill the bottle up halfway with hot (not boiling) water, shake it up, and pour it out. Repeat several times. If the bottle still needs more cleaning (which most do!), fill the bottle halfway with hot water, add a few drops of dish soap, and shake it up. Pour and rinse until the bottle is clean and not soapy. Hang the bottle upside down to dry.