I y aquired an old os 25 that you couldnt turn over by hand because of all the old fuel that was left in the engine when put into starage.. I disassembled it and soaled the whole thing in denatured alcohol for about 2 days and reassembled... It runs like new.. I probably have about 10 hours on it and still runs perfect.. Has anyone else ever done this to clean an engine.. Im pretty sure I'm not the first person to do this