Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Jim, I use air when I want to run cast iron cylinder engines like several Stuarts.  A few of my Stuarts do not have drain valves on the cylinders, so I feel better running air vs. leave moisture for rust to set in.  Also, it's a good option as a test bed.  BUT, by and large most of my engines do get steamed if they have brass/bronze cylinders.

Rog