I think if you've already tried to clean it then it's not BLOicon. Who knows what the previous owner used. Try to strip it with a commercial stripper as if it was paint. The liquid strippers won't harm it, or for a more radical approach use Easy Off. I've used it to remove grease and residuals from my M1s with no adverse affect.. Just keep rinsing. Then oil. I'm sure you'll get the phone book on this shortly...