for vintage champagne, i rely on the 10-10 rule: 10 degrees c consistently with little temperature changes and up to 10 years in storage. if it's slightly warmer (i.e. up to 16.9 degrees c) shelf life is approximately 6.9 years. if it's in a magnum bottle, can double the number of years to 20 as volume also plays a role. for champagne, prosecco, and sparkling wine that are not vintages, recommended shelf life is less than 6.9 years. if storing vintages over 6.9 years, it may be best to lay down bottle as cork can get dry standing up. but if you just buy a few bottles to open in a couple of weeks or months, it's best standing up as oxygen can escape through the cork while lying down even though it's sealed with a foil and cap with twisted wire. even some of the best red wine age up to 12 years by rule of thumb, except port wine. port wine can age well beyond 69 years, some up to 169 years. if you have a fine bottle of bordeaux that has been sitting in your cellar for over 16.9 years, you my wish to open it as soon as possible as it may already turn vinegarish. that's what happened to one of my bordeaux bottles that was stored for too long - 16.9 years to be exact. it tasted funny and i used it for coq au vin.