It looks like it's just oil then, according to the site. Just like the "lemon oil" situation, it's really counterintuitive and confusing to name something what it's not lol. That looks like it would work just fine, probably on par with F-One Oil
I wouldn't put a nut oil on any guitar I cared about. Did you just read about oiling your fretboard and realize you've never done it so went into panic mode, or is your fretboard actually showing signs of dryness and you're somehow desperate enough to use nut oil instead of spending ~$10 on a fretboard oil (I use F-ONE but you can also use lemon oil, mineral oil, or linseed oil (but just buy the F-ONE or similar as they're formulated for this very thing and have a better chance to produce the desired results).
It started of pretty light, but oiling it a couple times got it a little darker. This is what I use.
I like F-One fretboard conditioner. It both cleans and conditions without being sticky or overly oily. I haven't noticed an odor (it does have a very faint furniture polish like odor) after application, and it lasts for several months.
I've also used lemon oil in the past, and while some have really strong opinions about it, it's been fine for me. But since F-One is cheap, and a bottle of it will last you for years and years, I've been using it, and now prefer it over lemon oil.
Hope that helps!
Music Nomad makes a fretboard conditioner that can be used on rosewood, ebony, and maple. Here’s its Amazon link
You can get good stuff cheap on Amazon. Actual lemon juice (which is NOT the same thing as so-called "lemon oil" that's made specifically for fretboards) can ruin your guitar's fretboard. Don't risk your instrument just to save a few pennies, seriously. Many things on a guitar can be replaced, the fretboard isn't really one of them.
I've been using F-one oil for a couple years. It's a blend of cleaner and oil and safe to use more frequently than most other oils.
Pro tip: Use an old toothbrush with soft bristles to clean the fretboard. The toothbrush trick worked WONDERS on my maple boards when elbow grease and microfiber cloths weren't enough.
I've also use the synthetic 3M 0000 steel wool. Non abrasive to fretboards and also pretty inexpensive but that toothbrush is still my go-to.
Try fretboard oil to clean and condition the rosewood. The oil is up to you - I personally use bore oil, but F one (https://www.amazon.com/Music-Nomad-MN105-Fretboard-Conditioner/dp/B006WPGZAG) is really good too. Also get some 0000 grit steel wool and polish your frets. Its really easy and simple tp do just remember to tape off your pickups. All in all should be a 45 min job but makes a world of difference!
I've used this stuff on two guitars, a ukulele, and a mandolin and have no complaints.
I look at the fingerboard whenever I change the strings and if it looks dry I put a little bit on. You should get a small microfiber cloth to apply/wipe off the oil.
I would recommend Music Nomad's F-ONE Oil. There's a video on Amazon where the guy tells you why they don't use lemon oil in their product. It's really easy to clean and makes my fretboard look better. I do it once every month and a half/ whenever the fretboards of my guitars look dry.
I also recommend their guitar cleaning sprays (Guitar Detailer for satin finish & ONE for gloss, don't get them mix up!)
It's a combination of finger oils and toxins and oxidation from the metals. This is likely to be caused by having a low body Ph which make your sweat acidic. It's not harmful but if you'd like to stop if from happening you should increase your water intake (around 8-12 glasses a day) include more alkaline foods (green veggies). If you love Cheetos too much, just get this stuff, it's safe, lemon oil based and works wonders: http://www.amazon.com/Music-Nomad-Fretboard-F-ONE-Oil/dp/B006WPGZAG
This is really common with ebony. I blame it on mass-produced guitar companies not giving wood long enough to sit and dry before turning it from a tree into a guitar. This is a particularly gnarly case: the wood has dried and shrunk resulting in the cracking. See how the edge of the fretboard and the fret ends kind of waves up and down? I'm willing to bet you have some fret ends sticking out as well.
There are different levels of how to fix this: the "right" way is bring the guitar up to a stable humidity, remove all the frets, fill in the cracks with watered down CA glue + ebony dust, re-sand the fretboard face, re-fret. That's practically a $400 job, in my opinion. "Worth" is up to you, but to make them invisible again, it is gonna take some work.
If you're trying to save some money, first keep the guitar in a environment with a higher and -stable- humidity. 40-50% is a fine place, but in my experience, it matters more than it doesn't fluctuate. A case helps with this. Second, oil the fretboard. This is what I use, here's another option. Don't use lemon oil. Normally you take oil off relatively quickly, but spend a day putting it on a few times and letting it soak a bit over the course of the day, preferably in a case. That may be heresy to some people, but I've had that work in re-hydrating a fretboard like this and closing up cracks like this a bit. Over time if you regularly oil your fretboard (perhaps once a month), they should hopefully close up more and be less visible. Stable humidity + a hydrated fretboard will help a lot and is the cheapest option.