Some of it depends on your application. For example, if you are going to use a knife for food prep, you don't want something that can make you sick. If not, a shot of REMOIL or something like that is as good as anything.
I use mineral oil on most everything because (1) its cheap (2) it works pretty good on everything (3) doesn't get rancid like vegetable oil (4) doesn't smell.
But a lot of other oils work "better" because they don't attract as much dust, or are longer lasting or harder wearing. I would imagine that mineral oil might be a bit thick and sticky for a folder. There will be guys that come along soon enough to give you more specific advice.