As we are in the stage of storing/preserving, then in my opinion we need to oil the blade when it is dry or almost dry. I don't very strict with days of interval, but for myself, I think each every 2 or 3 weeks. If we are storing pieces which is not arsenic patinated, it might need a little more attention as rust will likely easier to grow on it. Still, I think it is actually not a problem to oil it as often as we want, as long as we are sure that we didn't apply too much oil to the blade surface, just a moist thin film of oil. Too much oil will not grow rust on our blades, but might left moist and unpleasent smell to the sheath, which I believe in certain degree will cause the blade to rust more easily. I uses paint brush (mine #11), and plainly all purpose mechanic oil (Singer brand), once in a while with some mixtures of cendana oil (ah, this one always too expensive

). Brush and wipe with soft cloth on smooth surfaced blades and I uses brush only technique on raw surfaced blades.
Now, I left the space for senior collectors to share their opinions...
Thanks!