Originally Posted by jbrians

oil on the outside of a chain prevents rust and causes dirt to adhere. Oil on the inside of the chain lubes he parts and minimizes wear. A flimsy 10sp chain will last a LONG TIME if it's run in a clean environment or in an oil bath....years and years.
I still believe that a good soaking in hot grease to get the stuff into the links will also tend to keep the dirt out which is why we get accelerated wear.
If you follow the path of a link as it goes around, you will see that the links of the chain under load always wear in the same arc. The smaller cogs force the links thru a greater arc so there is greater wear on the 11-14 sprockets. The bottom run is mostly slack so less wear occurs. Flipping a chain inside out really does extend use.