My Rasteau is half empty

It seems disgustingly prudent for me to drink no more than half a bottle with dinner nightly. I usually accomplish this in either of two ways. One is to freeze the remainder. Freezing changes the wine in two related ways, so far as I can tell: it very slightly reduces the acidity of the wine (which can even be an improvement with, say, acidified Australian whites) and causes tartrate crystals to precipitate, which is no more than a minor nuisance. I prefer, instead of freezing, to pour off half the bottle into a 375ml tight-sealing decanter when I open it, drink the bottle that night and the decanter the next. Sometimes the wine is better the second night (young Bordeaux), sometimes a little worse (Chianti) and mostly unchanged. Neither of these techniques will save a pinot noir: carpe diem or, at least, always find somebody to share your Burgundies with. Part of the fun is figuring out which wines will gain from being split, one way or another, over two nights. Until now, I had always chosen for the decanting young, hearty red wines, which I associated also with high alcohol. Yesterday, however, I read of some experiments in Bordeaux which suggested that alcohol speeded oxidation. Though these experiments seem loaded with bias because the easy conclusion would be that Bordeaux wines therefore outlast California or Australian wines, the chemistry seemed possible. So, last night I opened the highest alcohol European wine in my cellar. This was a Rasteau Domaine La Soumade Cotes du Rhone Fleur de Confiance 2000, at 15.5% alcohol. And a wonderful wine was the first days portion: rich, with a nose of red fruit and prunes and spices, with smooth tannins and a slightly oily texture. Today, the second half from the decanter, had the definite beginning of volatile acidity -- not a bad drink by any means but definitely on the way down. I'm guessing alcohol isn't the key to overnight keeping. I'll try this again, concentrating on a wine made from a grape known for anti-oxidant properties, maybe something largely mourvedre/monastrell.