Originally Posted by maltimpostor
The only reason you should be keeping the last 25% of a bottle around for an extended period of time is because it's not terribly good whisky. Otherwise, either you need to focus on what's important (drinking the good stuff) or you need to stop buying so many good bottles that you can't get around to this one for months at a time!
I glossed over the statements made prior to yours, I didn't realize the post was in regard to the idea that Whiskeys "get worse" with too much oxygen present in the bottle. That Statement may well be true, because alcohol evaporates very quickly. I can't say I've tested to see whether that has a large effect on taste.
If you are convinced it does, I would suggest one of two things or both.
1. A vacuum seal, like the ones that are commonly used for wine
2. Wine preserving gas. There are many types available, but the idea is that a mixture of inert gases (mostly noble gases like Argon, which has an ionization energy of 1520.5 kJ mol-1) can be used to replace the oxygen before storage. Non-reactive gas replaces the other gases in the bottle.
I've tested both these approaches with wine and got some very good results.