Wait, what?
"G-string constantly out of tune?
If your guitar’s G-string constantly falls out of tune, here’s a quick fix. Take a #2 pencil and gently roll a bit of lead in the nut-groove where the G-string lies. This helps add a level of friction where the string and the nut meet and keeps the string from sliding around during your performance."
Graphite is a lubricant. The string sticking in the nut is exactly why the string is out of tune.
Some of that advice was terrible and wrong.
You come at my fretboard with a flathead screwdriver, expect to remove the screwdriver from your ass.