Hi Tom,
I have used the Rail Zip on original Gilbert, new S gauge track (same look, size, etc.), and 3 rail tinplate, but others have used it on nickel-silver HO track. I'd say you can go several months before re-applying. But I'd work on the tender wheels first, let the product sit overnight, then hit the wheels lightly with a little piece of Scotch-Bright pad if there are any rough spots. Remember, and there will be a difference of opinion here, Scotch-Bright pads are abrasive and I never use them for regular cleaning, only to remove stubborn rust. The naphtha in the Rail Zip is a great cleaner and should penetrate any dirt.
Without the Rail Zip, my AF e-unit would need to be locked into the forward position for the train to make it around the layout.
Good Luck!
Take care, Joe.
