ok, one thing NOT TO DO,
Don't shake the bottle, then open it -
I thought I could avoid stirring it, but it did get through the screw seal -
I did use it on a couple of old steamers I had - a MP 4-6-2, and a Con-Cor GN S2 4-8-4 - just the side rods and a bit on shiny parts of the wheels - I did in fact, see an marked improvement in performance - not just imagination
thanks Max!