Yep, don't fly!!!!

All kidding aside, you're always going to get oil on the plane. About the only thing you can do it to cut down on the amount that gets on it. One of the better ways to do that is to put an exhaust deflector on the muffler. This will get the exhaust away from the side of the plane so you get less on it. You can also angle it so the wing or tail isn't directly in line with the exhaust. You can find them here: [link]http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXD636&P=ML[/link]