ORIGINAL: Sport_Pilot
Bearing seals are hermetic. In fact many are designed with a grease that will melt into a liquid at opereting temperatures. If the right materials are used they should work in two stroke model airplane engine.
Bearing seals are not hermetic -- they are close-fitting & are designed to retain high-viscosity fluids, not low viscosity fluids -- unless they have lip-seals --- & those won't stand 16,000 rpm.
Put some methanol in a sealed bearing & close it up -- the methanol will quickly leak out -- just like it leaks in.