I use such a product (Private Preserve) and it works pretty well. I think it is mostly CO2 and Nitrogen, with a smidge of Argon. I don't drink much wine so I h

I use such a product (Private Preserve) and it works pretty well. I think it is mostly CO2 and Nitrogen, with a smidge of Argon. I don't drink much wine so I have bottles in the fridge that have been there up to a year. When using the gas, I think the decay is more related to how often the bottle is opened and poured. So a bottle that I gas-treat after the initial opening seems to be happy to sit for quite some time. Subsequent treatments are not as effective.