Having tried the wire brush, 1/2 hour acid treatment, 2 coats of rust
preventative paint & finally 2 coats of rubberised underseal only to see the
horrible tin worm raise its head in only 3 months. I think I may have found
the answer at http://www.bhi.co.uk/hints/rust.htm.
Some other car people have tried it & been amazed as can be read at the
I don't know if this method has been posted before but its worth hilighting.