@Adriatic - I read your post, was that a response to me?
Yes. And expansion on other things here.
You didn't ask about after the rust is removed; but I hate doing a job twice
I've used pretty much every method here, just not necessarily on track. But metal is metal to certain extent.
If you ever need to ask a question etc. and I don't answer you, try an email (in my profile) I'm far from the "last word" but always willing to try and help folks. My net access is spotty. But I should be ok for a while again.
Just plain oil will remove rust. Soak, agitate scale, repeat. To maintain and really get it shiny; once cleaned the bad spots may "bloom" again. Clean with oil now. Wet it, wait a day, brush it clean say....twice a month (ten min. ?) After say 6 months, you can fall back to once a month, then twice a year, then when needed.
You wouldn't believe how things look after a few years of ten minute cleanings. "This was rusty junk?"
The mentality was taught to me by Gramps, who replaced cleaning his WW2 Army Garrand with Lionel trains. Maintenance never stops.