Perhaps, like me, you have the outlet from the exhaust pointing down. My OS 61FX powered Tiger also gets extremely oily, especially the top of the right wing.

A friend at the field suggested rotating the exhaust nozzle up instead of down. The theory here is that the exhaust will then flow over the wing instead of splattering on the wing. My only concern here is that the oil in the exhaust would have a "tougher" escape path, especially at idle.

I plan on taking a good part of tomorrow afternoon off to get ready for a pattern contest, so I will probably test the theory then. I'll check my C.G. and weight too, for your reference. My plane was kit built (partially by someone else, finished by me) and has no additional weight added, other that a 1000 maH battery instead of a 600 maH located as far forward under the fuel tank as possible. I probably would not even have had to do that, but I converted the plane from a "trike" to a "taildragger" shifted the weight of the third wheel from the front to the back.