You want tacky- rub between your fingers to see if it maintain tack. And you want no ready separation of oil. This is something your own experience with it might answer, if you have seen oil seeping out of greased area or such. I've seen Phil Woods separate over time in bicycles.
Moly is probably not the best. Maybe super tacky, start small, operating lever a bit to be sure to spread.
It occurs to me that there might be a 'better' way, although the above will work fine. More if you over-apply. I don't know the Copal exactly. There's a chance that the whole metal disk can be removed. You need to remove the lens group and see if the inner silver disk is just a washer. On many shutters, there will be three small screws with wide heads that hold the aperture disk in place, creating three 'tabs' on the inside of the ring. In most cases, this disk can be simply lifted away and replaced without issue. If you end up going this way, I'd recommend posting a photo of the back once you get the three screw heads visible. Soomeone might see something that says leave it alone! With aperture blades, disassembly for re-assembly is a long process, probably having you learn more about shutters than you want to.