13 days.
Also, Oblivion is quite old by now. I recommend mods. It's also the second most sandbox game ever released, right behind Morrowind. (though I would argue that Oblivion offered more choice, due to the radiant AI and faster combat; I remember when I put poison apples EVERYWHERE, and unleashed zombies across the Imperial City, which sparked a guards versus zombies war that lasted two days. Good times. ps, the zombies won; the dead guards kept coming back as more zombies)
Also, Oblivion is quite old by now. I recommend mods. It's also the second most sandbox game ever released, right behind Morrowind. (though I would argue that Oblivion offered more choice, due to the radiant AI and faster combat; I remember when I put poison apples EVERYWHERE, and unleashed zombies across the Imperial City, which sparked a guards versus zombies war that lasted two days. Good times. ps, the zombies won; the dead guards kept coming back as more zombies)