Hello Dave, I have also heard of the "Bon Ami" method, it was something that one of the older mechanics that I worked with many years ago would employ on trade-in tractors to help with smoking and/or low-compression issues. I do not believe I would do this to anything that was new or newer, but that's just my own personal opinion and not based on any supporting documentation to say whether it was detrimental or not. Best regards, Allan