Most glow oils will not "burn" during the combustion cycle. That is one of the reasons that they are chosen for model fuel. By being expelled unburned, they remove heat from the engine, as with all total loss lubrication systems. So, all that is really happening with glow four-strokes that funnel their lower crankcase oil back through the intake tract is that they are taking the chance of introducing swarf from the lower crankcase into the upper crankcase and they are ensuring that most of the waste oil goes out through the muffler, instead of a hose that is directed toward the ground. In the process, they are robbing a miniscule amount of energy from the engine's output. Not enough to be concerned about, I'm sure.

Until someone shows me absolute empirical proof that some of the oil is burned, I'll stick with my present opinion. Has anyone actually tried to ignite model lubricant with a heat source at the same temperature at which our engines operate? Good luck.


Ed Cregger