I had a guy tell me the same thing about clipper oil last year and I laughed at him right to his face. Then my trimmer started running hot and bogging down mid cut and I finally tried the stuff he recommended, some clear thin oil made for clippers, and it was night and day. The regular oil I was using just gummed everything up and attracted dirt like crazy. I felt like a real idiot going back to that same guy to admit he was right. So yeah, your Dayton guy is not nuts, he probably just saved you a trimmer.