As far as the B&C products go, my Grandfather would say if a product was good enough to be used on or protect his rifle, it was good enough for the trains.
I use B&C Sheath a lot. Lightly spraying w/pinpoint, maybe brass brushing any rust blooms from time to time until gone. I might use a deep penetrate carefully, not on paint/electric windings etc), flush it and more with cheaper wd-40 (including windings, and axle gunk, not all paint but some), and finish exposed metal with Sheath (or fresh lubrication oil vs a protective oil)