When my daughter was in 8th grade she did a science fair project similar to the experiment referenced above on MTBR by jnbrown. She tested six or eight rust preventative products on large nails that were buried in moist garden soil for a couple months. I don't remember all of the products but I do remember that regular WD-40 was one of them. The hands down winner...by a lot... was Rig Universal which is a a firearms protectant. I'm not sure how you would get it inside a frame because it is the consistency of vaseline. I have started using it on my bikes stored in the basement at the beach in NH. The house is literally 100 feet from the salt marsh. The basement has a dehumidifier but I would notice a light powdery rust on exposed raw steel parts when we would arrive in late spring. Now I give all of those parts a light coating of RIG before I close up the house in the fall and it seems to have stopped it.