We always ran our KX60s on 32:1 with no problem. Any good synthetic two-stroke oil is fine. If the bike has been over oiled previously, or the rider never really gave it any serious use, you may find the pipe is oiled up inside and, more likely, the silencer packing is saturated with the stuff. Get rid of it and start afresh. You will find when the wadding gets full it does drip over the wheel. It's a sign things need attending to but there is probably nothing mechanically wrong.