Your own natural oils from your body by just playing it more. Seriously, I have never oiled a guitar or bass fretboard in my 51 years of playing. I’ve read so much debate on what to use or what to never use so I haven’t used anything.
if you use a fingerboard oil, use is VERY sparingly. a little goes further than most people think, and you don't want to soften your fingerboard. my husband uses truly tiny amounts of mineral oil on our many fingerboards if they're dry. fyi - i wash my hands thoroughly before i play any bass with a maple board.
I am of the opinion that finger boards rarely need oil. When they dry out it is usually lack of humidity. If you oil, use very little and wipe off the excess. I would never use boiled linseed oil. It is a polymerized oil intended to be used as a finish.
Bore oil works great, too. As stated by others, just a little goes a long way. Wipe on, let sit for about a minute, then wipe off the excess.
oil doesn't moisturize wood, water does oil vs. water If you want it to look pretty for a while, oil it. If you want to moisturized it, do that, but it's not the same thing. I clean mine with a damp, clean cloth, because that's all it needs. BTW, if you use a Drying Oil, like Linseed oil, it can spontaneously combust, so be very careful disposing of the waste.
I hope this helps to sort out some of the confusing hype about a number of products that are frequently recommended when this topic comes up, and it comes up a lot. The following has information has been supplied by the manufacturers. Roche-Thomas Premium Bore Oil: 75% or more mineral oil Brite Bore Oil: 90% petroleum distillates (mineral oil, petroleum oil) Formby's Lemon Oil: 99% mineral oil, 1% limonene Old English Lemon Oil: 99 to 100% mineral oil Howard's Lemon Oil: 75 to 99% mineral oil, 1% Limonene Howard's Feed and Wax: 50 to 95% mineral oil, 1 to 5% mixture of parrafin, beeswax, orange oil and carnuba wax Howard's Orange Oil: 90 to 99%% mineral oil, 1 to 10% orange oil Weiman Lemon Oil: 75 to 100% mineral oil And from a distributor of Dunlop Fretboard 65 Ultimate Lemon Oil: "almost entirely mineral oil" As you can see, these products are mostly, if not entirely, mineral oil. There are a few products out there specifically for treating fingerboards that are not mostly mineral oil, such as Guitar Nomad's F-One which is made from plant-based oils. Many claim to have scientific proof of their effectiveness, but I have yet to find one that has been verified by an independent disinterested 3rd party. Draw your own conclusions.
I use Roche-Thomas classical instruments fingerboard oil. I use it like gun oil: one drop on a lint free cloth, wipe down, let dry. Of course, I use several Roche-Thomas products, most notably their valve oil, which has served me well for the almost 50 years I have played brass instruments, and my Dad playing trumpet before that.
FWIW Roche-Thomas Fingerboard Oil is also listed by the manufacturer as white oil, another name for mineral oil.
Plain old Mineral Oil you'd buy at the Pharmacy. it's good enough for Sheldon Dingwall and Fodera, it's good enough for me
I'm sure that it is mineral oil based, but it is anything but white. It is the color of the photo I posted. And it comes in the 2-ounce bottle (like a valve oil bottle) that will last for decades, so I don't have to deal with the larger bottle from Wal-Mart.
Boiled linseed oil isn't polymerized, but it will polymerize after application. The bad thing is, most commercially marketed boiled linseed oil contains poisonous metallic salts to promote the polymerization process. I would suggest only using consumable walnut oil sold for salads, or flaxseed oil sold for the same purpose. Linseed and flaxseed oil is the same thing. Both of these will polymerize over time and exposure to UV light, and seal the wood.
I use Dr. Duck's Axe Wax (which is actually an oil) most of the time, or if I'm out Gerlitz Guitar Honey. I've been very happy w/ either. A little bit on a rag, worked in, then followed up by a dry rag to remove excess. I do it when ever it looks like it needs it (usually every couple string changes/once year whichever comes first on the instrument in question).
I've used olive oil (yes i know it can go rancid but I'm not licking the dang thing). I've used lemon essential oil (smells great!). I've scrubbed with Murphy's oil soap (certainly will keep bugs away lol). i think it matters a lot less than folks say. haven't tried mineral oil but will do so next time i wash my hands well before playing any instrument. growing up my dad could always tell i had played his guitar by the finger funk left on it. never understood it until i had purchased my own instruments and had other people's grimy hands all over em