How long does Mobil1 last if not used, but installed...

Gas is double treated with stabil and lasts at least 2 years. I've run it 2 years old and it runs great. I don't let it get older than that before I pull it out and put it in the car and put newer stabil treated gas.

I'm on the fence here. How long does oil sit in a container before it is installed? I hate to change out oil that seems perfectly fine, but I don't want to risk anything either...