How long do you keep an unfinished bottle of rum?

Earl: When I first started this rum journey more than 3 years ago, I started out like most other newbies to premium rums and stocked up on the sugar bombs and sweet rums. I was so proud of my collection and expected it to last more than six months. The longest that I ever had any spirit last was six months for a bottle of Pappy Van Winkle 15 Year Bourbon (back when it was only $70 instead of thousands). Well, to my utter horror, any heavily sugared rum with 20 gpl or more of added sugars will cause the flavors to deteriorate once the bottle becomes half full. I then recommended 4 months maximum shelf life for these sweetened rums, but any within less than 2 months of being opened should be fine. I also live in a sub-tropical climate and make sure to keep them out of any sunlight. Well, there went my notion of collecting rums! And with added sugars causing me to be married to the royal porcelain throne the next day, this was my second reason for staying away from rums with 20 gpl or more of added sugars. These two reasons caused me to slowly appreciate dry rums and rhum agricoles, and those are all that I buy now. There is an occasional foray into new coconut or spiced rums, but that is about it. I like them, but they don't like me. After my awakening on how rums can deteriorate in the bottle, I now have a column in my spreadsheet for Date Opened. Most are in heavy rotation and only last one month. That will now slow down even more. In lieu of a spreadsheet, one can place a piece of freezer tape on the bottom of the bottle to mark the Date Opened. So my simple answer is that I have never had a bottle of rum last more than six months, let alone like the ones that you found stashed away. Now if they were never opened, they should still be good.

Paul. Great response and lots of good points again. Thanks for your input. I like sweet rums which is why I don't have many unfinished bottles in the 20+ GPL range, but I am working my way towards finishing a rum within 3 months of opening it. Definitely going to do some spring Drinking...er Cleaning to clear up these unfinished bottles. Some may be disposed of and the others might make it into a blend for immediate consumption. Cheers.

I had a Captain Morgan Original Spiced, from 2011. It had one last gulp, inside. Finished it up, last year (2020). I now have my first Chairman's Reserve 1931, almost empty; it has only one last serving, inside! I plan to drink it up when my life is about to end or something. All others are gone; Why is the rum always gone?

In all honesty I never had a bottle of rum opened for longer than a couple of months with 7 or 8 months as a max. In reality most bottles are empty within weeks, not months. I don't think (dry) rums will really go bad but will loose a lot of flavour whether through oxidation or by loosing the more volatile ingredients. @Pirate: I would not wait too long with that 1931 when the bottle has just one serving left; give yourself a nice excuse to finish it soon, find yourself the next best thing, buy at least 2 bottles and keep one unopened till your final days! :-)

I participated in a Cognac course some years ago led by the Master Blender of Grönstedt’s Cognac. At that course I learned that a bottle represents 1 year when first opened. The time the content still tastes as it should depends thereafter on how much you drink that first opening. 2 examples: 1) If you drink 1/3 you should finish the rest in 8 months. 2) If you drink 2/3 you should finish the rest in 4 months.

@Harrie That actually is really tempting, since the final serving of this rum, contains edible solids (resting at the bottle's bottom), that bring an explosive taste with a mind-numbing, wild sensation (No81 had solids, the Chairman's Reserve has powdered remnants)... But i really need to reserve it! When i fully succeed in restocking, then i will still keep it intact, since the last serving is always the best serving (refer to my review of No81)! @Stefan Persson Thanks for sharing the professional information with us and presenting it to everyone! This community is both friendly and helping; trully exemplary! Makes somebody really glad to hang around!

@Pirate: My online vendor doesn't ship to Greece but I did found one in Belgium that does though the website doesn't state the costs of that. Unfortunately the webshop is only in dutch but I think you could send them an e-mail in english (most dutch-speakers do have a basic knowledge of english) for an inquiry. This is the 'map' with the treasure; https://den-hoorn.be/product/chairmans-reserve-1931/

Update on what to do with unfinished rums. I put a couple of drops of distilled water into my Appleton 21 and it changed the taste to where it was enjoyable again. Like they suggest with Scotch, adding some distilled water will open the taste profile and it's true.  I am still going to finish this within the next  month but for now I would say it's been salvaged from the drain or relegated to the mixer category. 

I have an opened bottle of Zacapa 23 from last year's September and another full bottle I got for Christmas (my family and friends still believe that Zacapa 23 is a perfect rum gift for me...). Your discussion inspired me to do a back-to-back tasting of these two. As the rum is highly sugared I should be able to feel the difference.I also have two samples of the basic Hampden so I will try to see if there is be any difference for an unsugared rum. Can you also do similar tests? I mean not based on memories (I don't feel I can store precise information about taste and smell in my mind for too long) but on a direct comparison. 

Any booze will go down in proof as time goes by. That's why I like overproof bottlings!

I always buy one bottle and finish it in a month and buy then a new one

Sweet rums go south the fastest, because they are actually often underproof (in contradiction to the labels) - a 40% ABV sweetened rum is often in reality only 38%, but sometines even 32%ABV, because these drinks are for people who actually hate the taste of alcohol. So if the producer substitutes some of that declared alcohol with the mixture of water, sugar, adulterants (sherry wine, glycerol, dried fruit extract) and aromas, it's a win-win situation, because alcohol is relatively expensive compared to water, sugar and aromas, and most importantly, each % of alcohol is heavily taxed by the government (at least here in Czech), so the producer will cut his costs, while the consumer will get a drink that is "smooth, luscious, silky, warming, friendly, cozy, homely and soothing". I think there are people who would be happy to drink liquid candies from their rum bottles, if only there were pirate ships and parrots on the labels. ;-) @pirate - if there are flavor intensive solids left on the bottom after emptying a bottle, it's the best proof of adulteration. Remember - no molecule significantly heavier than alcohol passes the distillation, so any such residuum would have to be provided by the barrel during the maturation - and from just charred and toasted barrel, you are unlikely to get anything similar. Of course, if you "forget" a significant portion of Pedro Ximenes sherry in your "empty, but used barrel", you will get a flavor boost from it. Or you can "accidentally" drop a brick of panela into the barrel - what do you know, accidents happen, especially when they "improve" the rum! ;-)