Using Proline Fretboard Conditioner? (Residue??)

That doesn't look normal. I would try to clean it all off if you can. I doubt it will hurt anything, but it shouldn't show up as an accumulation in the pores like that. Possibly it is reacting with some previously applied oil or cleaner?

If I use any oil at all, I use just the slightest amount of mineral oil. I use such a tiny amount on a small cotton patch, that I have to rub it a bit to get it onto the fretboard. Looks nice and is virtually dry when done.

Opinions vary a lot on this subject.

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Most lemon oil is just mineral oil and a lemon scent (and possibly a cleaning solvent).

If the residue is stubborn, try a soft brush and some naphtha (Ronsinol lighter fluid). Soak it up immediately with some paper towels as you brush. Naphtha is safe on virtually any finish. You want to soak it up right away so it doesn't run off and leave the residue behind elsewhere on the neck.

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