I'm going to get on my fretboard oil soapbox for a minute. I've mentioned this before on this forum and I know some people will disagree, but I think it's an important educational point, so here goes.
Oils basically fall into two categories - drying and non-drying. Drying oils will cure to a hard finish - non-drying oils won't. Most guitar-marketed products are mineral oil (which is non-drying) cut with some other oil (often lemon oil) or a volatile solvent to make it thinner and help it clean up any remaining gunk when you apply it. But, it doesn't really matter - there really aren't any important functional differences between the various non-drying oils. When applied to wood, non-drying oils will partially soak in and partially evaporate (which can take months). That gives the impression that the wood is "dry" again, a few months later, which triggers people to want to add more oil. Over time, this repetition basically means the wood slowly becomes soaked in oil.
The problem is, oil-soaked wood is difficult to work on. If you've ever tried sanding a board that's been soaked in mineral oil, it's messy. You get a sticky paste on the sandpaper instead of nice powdery dust. And gluing oil soaked wood? Forget about it. Some common fretboard woods (especially rosewood, colobolo, etc) can be oily enough on their own that they're already hard to glue. Adding your own oil makes it worse. Doing fretwork on oil-soaked wood can be a challenge, too. The oil lubricates the wood, so frets actually go in more easily - but they also come out more easily. It can be maddening to try to get a fret to go in and stay put in an over-oiled fretboard. Normal tricks like using CA glue don't work, since the CA doesn't stick to the oil-soaked wood. Upsizing the tang on the fretwire to get a tighter fit can work, but then you run the risk of wedging the neck into a back bow.
Most people who oil their fretboards will never have to deal with these issues, so it's not like it's not like the most serious problem in the world, but for the times when issues do occur, they can be difficult and frustrating to deal with. I once worked on a guitar that needed fretwork and fretboard binding repair. The fretboard had been oiled so frequently, for so many years, that it was basically beyond help - we ended up deciding to remove and replace the fretboard. The owner was pretty distraught. He thought he was doing the right thing by "taking care" of his fretboard. Instead, it turned what should have been a few quick fixes into a major surgery.
So - I'll repeat what I said above. If you keep your instrument humidified, the wood will be stable all on it's own. You don't need to oil it to try to lock in moisture. And if you keep it clean, the fretboard will always look good. There's no need to put oils on it.
But what if you like the look of a polished, freshly oiled fretboard? They do look great! Or what if you can't control the environment, or you have dirty fingers, and you want the protection that oiling provides? If you're really worried about protecting your fretboard, leave the non-drying oils alone and use a drying oil finish. They will cure to a hard and permanent protective finish, and will help lock moisture (water) in the wood, keeping it stable through humidity changes. And they will avoid the problems you get by soaking non-drying oils into the wood of your fretboard - a cured oil finish can be sanded, glued to, and otherwise worked with or repaired just fine. There are oil finishes that can be wiped on with a cloth just like fretboard oils, it takes a few minutes and is literally no different in terms of the process. Or you can have a tech apply the finish if you're not sure. There are a number of finishes that can be used, my personal favorite is stew-mac's Colortone fretboard finishing oil. It goes on and cures very thin and gives the wood a permanent just-oiled look that's easy to clean and take care of. The bottle they sell it in is expensive, but it'll last most people a lifetime (literally - it's probably enough for at least 50 or 100 ukulele sized fretboards).