My LO206 engine has been accumulating this black grease or grit on the front of the engine down by the chassis. It is also around the carburetor and I don't know if my engine is leaking oil or if this is normal. When I run my engine it runs and sounds fine and I don't notice any loss in power but I don't know what this stuff is on the engine and how it is getting there. Does anyone know the answer to this?