I have 2 Castile bars (100% Olive Oil) that I am hoarding. They are 5 years old. So good!Give it a try! But withhold judgment until 6-8 weeks. it's probably not going to lather as well as you'd like,and also leave your hands kind of dry and chapped feeling.
Ever so often I stumble across a bar that's 5+ years old...it's amazing how nice it is. I think that one day, well-aged soap will absolutely be a "thing".