batman wrote on 02/16/20 at 16:37:21:While we seem to be concerned here with oil / fuel vapors, that may or not be burned in the motor , that's nothing compared to what's leaving your exhaust pipe . IC ( internal combustion ) engines ,gas and diesel efficiency , only runs between about 20 to 30 percent , the other 70 to 80% ( gas favors the lower end of the span)passing out the exhaust is much worse than the fumes from the breather hose.
A brief review indicates that while it is true that only 20-30% of fuel is typically thermally converted to useful energy, a modern, conforming engine successfully burns all but a fraction of a percentile of fuel. Tail pipe emissions, while linked, don’t relate directly to energy conversion efficiency- that is, just because energy isn’t harnessed doesn’t mean it wasn’t converted to heat, exiting as a proportionate constituent of exhaust emissions. While the volume of emissions from the crankcase and exhaust differ radically, so does the character and liabilities- that, after all, is why systems are contrived to confront crankcase emissions. It’s a bit of a non sequitur to claim venting the crankcase directly to atmosphere is no big deal simply because there is comparatively less of it- akin to saying “don’t worry about the low levels of lead and mercury in this ice cream, as it contains far more cholesterol”.