Telemaster is correct, glow fuel is no problem as long as its not left to sit in the engine. When that happens it attracts water and things go very nasty. Generally 4 strokes are more resistant to rust than 2 strokes as they never have any raw fuel in the crankcase which is why I personally think the intake mod for the 400 is a bad idea as raw fuel is being introduced to the crankcase. That said, if an engine is run regularly its far less of a problem