You should oil your fretboard once or twice a year (or every 6 to 12 months). The goal is to keep the wood hydrated and prevent it from cracking. More frequent oiling isn't necessary and can actually cause glues and inlays to loosen.
Oiling the fretboard is part of properly hydrating your guitar. Rosewood can dry out in some climates so one annual application of a small amount of mineral oil can help, especially after cleaning the board. Ebony is usually oily enough not need attention.
In music, the 3 Fret Rule (or "3-fret hack") is a popular shortcut used on guitar and bass to easily switch between major and minor keys.
I've tried it just on my fret hand and it worked great. Not sticky and doesn't get gummy but I'm concerned how this will affect the neck and fretboard over time. It seemed like a crazy idea, but after trying it, it worked better than anything else I use.
Adding needed oils back to the wood, like those in our F-ONE Oil, will keep your fretboard playing great and hydrated all year long. A good rule is that if your fretboard looks pale, feels rough, or plays slower than normal, it's time to condition your fretboard.
The industry consensus points to MusicNomad Fretboard F-ONE Oil as the best all-around fretboard oil. It is 100% natural, free of sticky waxes and petroleum distillates, and is highly recommended for effectively cleaning, conditioning, and protecting unfinished wood fretboards like rosewood and ebony.
As always, I recommend moderation with oils and waxes. I have seen loose frets caused by overzealous oiling, and please don't treat any lacquered or finished surfaces with oil—it will not help them and can actually cause problems.
This one's a little different, but here's another treatise on fingerboard "treatments." Folks used to use vaseline (white petroleum jelly) in their fingerboards “back in the day” when they wanted to make the fingerboard and strings feel slick.
A couple drops of Dawn and warm water on a damp rag and then buff dry. I never use polish. This one is 35 years old. Bob Prosser nice guitar!
In guitar culture, there are two common answers depending on whether you mean musically or culturally:
Jimi Hendrix was known to count frets on his upside down, right handed guitars, likely to ensure he was in the right position, especially when playing with his left hand.
To oil a guitar fretboard, start by removing the strings. Dab a small drop of specialized fretboard conditioner or 100% mineral oil (like Dunlop Lemon Oil) onto a clean, soft cloth. Rub the oil gently into the wood, let it sit for a few minutes, then wipe it completely dry.
Acoustic steel string guitars are harder to play than nylon string or electric guitars. They need about 30% more finger pressure to fret notes correctly. Thicker bodies and wider necks make them more challenging. These features are common in expert level acoustic guitars.
Sunken top across the soundboard between bridge and fingerboard. Back of guitar looks very flat when it is dried out. Sharp fret ends extend beyond the edge of fret-board. The plane of the neck angle on a dry guitar hits above the top of the bridge.
This means that using a polish or wax will only exacerbate the problem, so it's best to wipe a dry cloth very gently onto the guitar's surface and to avoid cleaning solutions. Satin-finished guitars offer more of a semi-gloss look, but have a similarly smooth feel like matte-finished instruments.
It is not recommended to clean a guitar with Windex. While it can occasionally be used on modern polyurethane finishes, the ammonia and harsh solvents can damage delicate wood and strip certain finishes over time.
The best guitar cleaning products depend on what you need to clean:
Actual lemon oil is caustic and bad for your fretboard. Use either mineral oil or linseed oil.
Boiling bass strings acts as a cleaning method to remove built-up grime, sweat, and oils from between the windings, which temporarily restores brightness and extends their life. This process breaks down gunk that causes a "dead" sound, bringing back about 75% of their original, punchy tone, though it cannot fix physical wear or deformation.
If you only got it on the fretboard, it will be fine. Use naptha to remove any residue left by the oil in the wd40, then re-apply a small amount of lemon or mineral oil. If you got it on the guitar finish, it may react and damage the finish, just depends on what the finish is made of and how long you left it on.
I remember when I was young I always had old strings. I got a couple of sets. Generally, no it is not harmful to the guitar, unless the guitar has serious issues - issues that would cause problems with or without strings. It is not uncommon for guitars to sit or hang un-strung for weeks or even months in repair shops.
Among the oils you mentioned, I'd recommend using pure tung oil for your guitar neck. Smooth feel, excellent protection, and looks good too.
Let fretboard oil sit for 5 to 10 minutes to allow the wood to penetrate and absorb the moisture. For very dry fretboards, you can leave it for up to 20 minutes. Always thoroughly wipe off all excess oil with a clean, dry cloth.