A machinist friend of mine swears by Kroil, to the point of derision by others when the subject comes up. Many years ago, one of my buddies drilled out a steel plate and welded in like 8 bolts to it. We buried it in his back yard near the wetlands part of his lot and planned to dig it up in two years and use it as fairly well controlled test bed for various elixirs. Unfortunately, he moved and we forgot to dig it back up.
Most evidence I've found on the subject is anecdotal. Without a control there's no way of knowing if one of these solutions would have worked better or worse than any other.