Obsidian Pipe Stem Oil isn't a wax or a cleaner. Obsidian Pipe Stem Oil is specifically designed as a preventative to help keep your vulcanite, ebonite, or Cumberland stems from oxidizing and help keep them looking newer for longer. In addition to conditioning and sealing the pores of the vulcanite, thus resulting in much less oxidation, Obsidian also contains small amounts of organic quality UVA/UVB protection. Unlike Olive oil, which some people use (and will go rancid), Obsidian has no taste and is specifically designed for use with rubber.
After smoking, wipe off the stem. Apply a few drops of Obsidian oil to the stem and rub in. After 30 minutes, wipe the stem with a soft cloth and store as usual until your next smoke. Obsidian should not be applied to the briar, only to the stem. It will make the briar look shiny but it will also clog the pores of the wood, resulting in a hotter smoking pipe in the long term. While it will help make a badly oxidized stem look a little better, Obsidian works best when used on a new pipe, or newly polished pipe to help prevent oxidation for much longer than normal. The more you use it, the better it works, however, that doesn't mean it's needed after every smoke as long as the stem is wiped down after every smoke.