Well, Prof_Pastry_UK, your inquiry about "spoilage" is a bit broad. Are you referring to oxidation, microbial contamination, or just a loss of aromatics? It's important to be precise when discussing chemical processes.
Regarding preserving opened wine, the principal enemy, as your experience suggests, is indeed oxygen. Your methods, such as vacuum pumps, are conceptually sound, but they often fail to remove *all* the oxygen, or they remove too much, which can also harm the wine by stripping delicate esters. Inert gas, specifically argon, is demonstrably more effective because it's heavier then air, creating a protective layer. However, you're technique for application is crucial. Ensure a proper, complete flush.
Furthermore, temperature plays a vital roll. Lower temperatures significantly slow down chemical reactions. So, inert gas and refrigeration is your best bet, IMO. Think of it like preserving a delicate plant; you need the right environment and protection from harsh elements, BTW.
