I've found this to be highly dependant upon the oil used ( the messiness part )
I too would recommend the 10cc 10GX, read the manual and follow the instructions to a T and you shouldn't have too many issues.
ORIGINAL: skillet92
Got a fellow club member that is all glow and bought the evolution 10cc for a tiger. While the engine is smooth running and easy starting engine. It is also just as messy as glow because of the 20-1 oil required. I would love to know why the OS 40cc can be ran at 40-1 and saito and evolution have such high oil requirements. All that being said I still think it is a good value for what it is. He can't go wrong with the engine for that plane.