The ESP Guitar Company

use an old toothbrush for getting al the fingerfunk out. you could use some rubbing alcohol... after that use some kind of cleaner like the jim dunlop cleaner & prep 01..after that you could use the deep conditioner 02(I don't use that)... and last but certainly not least, the jim dunlop lemon oil 65
Jim Dunlop stuff

if you want to make your frets look shiny, use steel wohl (0000 grade)

Not sure it will get you back to the exact same as the guitar was when it left the factory, but I always use Selmer clarinet bore oil to oil all my guitar's fingerboards.

BTW, oiling a fingerboard after every string change is way overkill, but I guess that depends on how often you change strings. You can overoil a fingerboard to the point of causing more harm than good. I personally oil my guitar fretboards probably around once per year. I don't actually keep records and it probably goes longer than that with some guitars and less with others.

Lemon oil/orange oil (not pledge) is best to use. I occasionally take a swab of 0000 steel wool like I use after a crowning, except without the wood taped in order to clean if notably funky & open the grain a bit. Also a cut credit card can be used to scrape the edges of frets to get hard to reach crud. I typically oil about every 3-6 months on guitars used frequently.

Not a big fan of rubbing alcohol on unfinished woods as the citrus oils have enough of a solvent quality to get most sticky crud off (like dried beer/blood and such).

Gerlitz Guitar Honey

using a square pencil eraser is good for getting the built-up grime off also

olive oil, light light steel wool.