it is normal for glow engines to exhaust some unburnt fuel and of course all the oil. the fuel is approximately 80% burnable stuff (alcohol and nitromethane) and 20% oil. the oil does not burn. it just flows thru the engine to provide lubrication and cooling.
But it sounds like you are running the engine too rich (needle valve opened too far). You need to find the sweet spot in the needle valve where the engine runs best. too lean (clockwise) and the engine will not get enough fuel to run. too rich (counterclockwise) and the engine gets too much fuel. Your symptoms sound too rich.
But even at the perfect setting, there will be alot of residue on your plane - mostly oil.