I did it myself, but I used a Penzoil product intended for rustproofing internal parts of marine engines. It was $3 for a 12 ounce can in the automotive department at Menards. Removed the seat post and water bottle screws. Inserted the small plastic straw in the spray can nozzle. Sprayed some in all the opennings including the drain holes in the chainstays. Turn the bike upside down and slosh it around.