I have tried to get to the botton of rust removers and inhibitors. Oil in itself is rust inhibiting, the added substances vary from maker to maker. I haven't managed to get a general view of them, but on the bottles are alkanolamine salts, alkylbenzene sulfonate, polyethers, benzotriazol and molybdenium often mentioned. These are the additives typically 1% or less of the full content, I have no idea what they are. There's rarely a full list of ingredients, often secret recipes and a pinch of hype, they tend to work though.
There are two oils they sell in bicycles stores I have bought repeatedly for years now; Triflow and Finish Line Ceramic Wet lube. They are both much the same light synthetic oil with added teflon, noticeably a notch or two better than the basic mineral oil. Bike oils are usually thicker than sewing machine oil, often added a sticky agent to make it coat chains and stay there in all kinds of weather. Because of this they can be very gooey. Triflow is sold as an all around type lubricant, the Finish Line Wet Lube is marketed for bikes but its' a very nice oil, very light and clean oil, coats the metal well and will not gum if it gets the chance to dry up.
Rust is this weird stuff, it coats surfaces and makes parts fuse stuck with corrotion. When oiled and unstuck; as gears and hinges get's used again rust sort of dissolves, it flushes out like a dust and residue in the oil. I usually get it all off, but it can take time and several rounds with cleaning, scrubbing and oiling. Using the machine regularly is often the best medicine.
This subject is an ongoing thing for me, both when I tend to my bikes and when I take over an old sewing machine.