I have a bottle of penfolds bin 389 vint. 1990. I have very little knowledge of wine, even though I have a degree in Culinary Arts (I ended up becoming a firefighter). I was wondering if anyone could tell me how I might be able to tell if the wine is still good and when should I drink it or should I leave it alone for now? Since I've had it, it's been laying on its side in a dark closet, I kinda knew that. Before that I'm not too sure how it was stored. Any help would be greatly appreciated.