Luke,
I think what both Larry and I were trying to say was that regardless of how hard the carb is sucking, if there is virtually no vapor from the oil then there will be no oil vapor being sucked in. If you want to try an experiment, put some 30 wt oil in a glass bowl and set it outside and see how long it takes to evaporate. The more vapor a substance creates (higher vapor pressure) the faster it will evaporate.
Additionally, if the dust particle is so small that it is floating and being absorbed into microscopic oil droplets, then I doubt very seriously that it could cause any harm to your engine. Ash particles created by incomplete combustion of gasoline (and there is never complete combustion) would be many orders of magnitude larger than such dust particles.
With that said, I would never argue that an oil-bath air cleaner is more efficient at removing dust than a modern paper filter. I'm simply stating that minimal amounts of microscopic dust and oil are going to be the least of your engine woes, particularly with an old stovebolt
.
