I unpacked a clamp style food grinder

[TommyT139]

2. Food grade mineral oil

Especially if you are selling to collectors of vintage ironware, do as little as possible. After all, if someone is going to use it for food prep, they will clean it anyway, according to their own preferences. The oil doesn't have to fit the bill for seasoning, which is best done with other oils.

Since it has no rust, you might want to use a thin coating of food grade mineral oil, which has minimal additives classed as edible. Using another oil would likely keep the rust away, which I assume is a goal, but depending on what kind, is likely to get "tacky" and either attract dust or stain a box.

Here is a reputable-sounding article:
https://www.seriouseats.com/mineral-oil-is-good-for-cutting-boards-and-knives

Good luck!