I've started to add oil and oil lanterns to my supplies. I already stock propane, kerosene, and candles for lighting, but feel it is wise to have as many options as possible. I've noticed that the metal frame lanterns I buy say to use only kerosene or oil, depending on the lantern. However, they look identical. Will they function with either fuel? Also, in everyones experience, which fuel would you say is more efficient? Lantern oil is around $6 for 64 oz. and kerosene is about $3.75 a gal.