Just bought some string cleaner (ghs fast fret) but now not sure if I should use it. Any thoughts any one? (i normally use lemon oil on the fretboard when I re string)
Go for it, just be careful when you apply it and follow the directions.
I use GHS fast fret. Just take it out of the packaging and rub the smelly side on your strings. Firmly. Let it soak in for a bit then use the cloth that they provide to wipe off any excess. It works pretty well. Cleaned some rust off my bass strings.