I've got a steel cyclocross frame I've ridden for a couple seasons. I didn't get around to treating it with Framesaver before that, and after a couple of race seasons there's definitely some surface rust inside the frame tubes. I plan to treat the frame with Framesaver while I have it apart. I'll also be drilling a drain hole in the bottom of the BB shell. The most easily reachable areas (BB shell, seat tube) I plan on cleaning with a wire brush, but there's some rust on the surface in other places, too. Is it necessary to treat and/or remove this rust before applying Framesaver? If so, how?