Need Better Ideas To Preserve Whisky...Help!

I read about someone who uses marbles or glass beads to keep the bottle "filled" after opening it. I haven't tried that yet, but was considering it when I open some of my nicer bottles.

What was the total length of time during which the bottles were open? It is true that some whiskies are more sensitive to air exposure change than others, and I have certainly found that lower proof whiskies with delicate flavours are more susceptible.

I like Private Preserve Gas, and have found it to be very useful, yet I don't think that it is fair to ask it to do all of the work by itself. I see it as more of a strong retardant to air aging, rather than an absolute preventive.

Decanting to smaller bottles with very small air exposure is more reliable over a long period of time than is gassing, I believe. If I were you I would quickly decant any whisky with which I had a previous early problem with degradation of flavours.

@Victor Maybe with the lower ABVs, but personally I have always found that most of my bottles improve with oxidation. In fact I rarely enjoy a newly opened bottle half as much as I do when I return to it 4-6 weeks later.

@olivier, oh, yes, certainly the vast majority of whiskies improve with air in the first few weeks after opening the bottle. I was referring to much longer times of air exposure often endangering the quality of the whisky. The nature of the changes with air exposure is highly variable according to the particular whisky and the particular conditions involved.

I try to finish a bottle within the span of one year. The only bottle that seemed to be deteriorating over time was a Glendronach 15yo

For me decanting is the way to go. Once an open bottle reaches the halfway mark I look to decant it into smaller bottles (keeping out as much air as possible. And then when that bottle reaches the half way mark it goes into smaller bottles.

I have done a few experiments (and I have one still going) where I take two of the same bottle (and batch) and pour of samples starting with the day the bottle is opened, then 6 months, then a year (and now two years).

I did this with two bottles of Ardbeg Uigeadail L11 028 a while back. One year after opening the first bottle I opened the second bottle and compared it with 50mL samples I poured off on the first day the bottle was open, 6 months later, and finally the last two fingers left in the 1st bottle.

My experience is that the 50mL sample poured off on the first day the bottle was opened retained over 95% of the original character that a fresh bottle has after one year. The 6 month sample was very close to the original . . . but by the time a bottle had been open a year (and over half that time it was less then 1/2 full) it had really mellowed out and lost much of its vibrancy.

That is just one personal experiment with a heavily peated malt at 54.2%. Your experience might vary.

Sounds like decanting might the best idea after the whisky gets close to 1/2 full, and using private preserve until that time. Wondering what kind of decanting bottles some of you might be using? I have come across some forums that mention screw caps being a problem with future degradation, but it seems finding a bottle stopper cork for decant bottles is hard to find. Someone mentions the "The Clear Boston Rounds" at "Specialty Bottle" on a different discussion here. Maybe electrical tape around the seal would work fine with this bottle, but any opinions on specific decanting bottles would be welcomed.

Just as a side note, I'm finishing a bottle of Highland Park 15 tonight (last 1.5 oz) that has been open for 16 months with the last several months having less than 20% in the bottle. Despite all that head space, it seems to have held up just fine with the Private Preserve. A Longrow 14 also about 16 months and with about 1/4 left is drinking quite nicely as well. So as others have said this phenomena is very random to which bottles suffer. Antidotally, my experience is telling me that older whisky's are much more vulnerable as I've only had one other whisky go very south besides the two I mentioned earlier (JW Blue). Comments are greatly appreciated...thanks for the ideas! Again, i'm leaning towards decanting older bottles and as some have said any whisky I've had problems with in the past.

Keeping air out is still the best way to preserve a whisky IMHO. The gas helps, but as @Victor says, don't rely on it to do all the work, particularly in a less than half-full bottle.

Drinking within a year seems like a sound guideline as well, although for some (looking at you @Victor!) with large quantities of open bottles.. YMMV (your mileage may vary).

I find my cask strength whiskies and/or those with bold flavours hold up to oxidation much better than the lighter more fragile whiskies at 40% ABV - or perhaps it's just a case of noticing a change more in the latter as they are most susceptible to adverse change.