I recall back in the days of my supposedly misspent youth there was Bardahl Top Oil and a few others that were supposed to provide better lubrication to valvestems and lengthen the interval for valve service according to the ads in magazines.
The guy with the really cool car had a glass jar under the hood that bubbled topoil into the intake manifold in a manner that supposedly gave superior results to just dumping a can of Bardahl in the gas tank when the car was filled up.
Best I recall the first few vehicles I owned pretty much leaked enough oil along the valve stems and guides to make some smoke and convince me I didn't need to consider top oiling. The concept seems to have slid off the radar in the years between then and now.
Today I had a conversation with a man holding a top oiler jar in his hand saying he is thinking of installing it on a propane engine that was originally gasoline to provide valve stem lubrication.
I did some searching and learned Ampco is still producing the devices,
http://ampcolubes.com/about_usAnybody have experience with topoiling on flathead engines?