I have a riding mower that is cleaned once per year. THe mower is about
5 years old. Problem: by the end of each season, there's a build-up of oil on the lower part of the engine. This oil accumulates dust and clippings and results in smoking (near the exhaust). Most of the oil build-up is around the muffler. It's almost like oil is being slowly spewed out the muffler and then builds-up from there. Oil is NEVER overfilled. Any ideas on the cause and remedy?