Re: Do you have to take off strings to apply lemon oil on a fretboard?
I have used Fast Fret for over 20 years, and I really like it. On my maple neck Peavey (clear finish), after playing I apply FF the whole length of the strings and to the fretboard. Using a cut-up old cotton sock turned inside out, I wipe down the top of the strings. Then I slide the sock under and through the pickup area and wipe down the backside of the strings & fretboard using the 'furry' inside of the sock to clean in close to the frets. While there, I clean the underside of the bridge with a quick buff of the sock, then pull it out and give the guitar a quick overall wipe off. I do this before putting it away because we live about a half mile from the ocean, and in a high humidity salt environment, things with steel like to get a bit rusty if given a chance.
This way, it is ready to play right out of the case. And it always looks nice too (nothing wrong with that!). With my 12 string acoustic (rosewood), I apply FF before and after playing as I play it less frequently and bronze wound strings do not like salt air. Plus the fretboard soaks up the FF application before I get it out to play, so the quick wipe before playing refreshes it.
About twice a year, I apply a bit of lemon oil with a clean sock scrap to the acoustic. I found a way to do it without pulling the strings, and it works real slick. Use several thin layers of plastic (strips of garbage bag plastic works well) to back the cloth you have applied a bit of lemon oil to, slide it under the strings with the plastic against the underside of the strings and the cloth against the fretboard. Wipe the neck (up & down as well as across it) to apply the oil, then pull it out and slip a clean piece of cloth in and buff it off. Fast, easy and no need to mess with the strings.
Just thought I would relate how I have done it. I am very happy with the results, and it works well for me anyway. One other thought I have had but never really talked about with other players is one possible benefit of lubricating with FF regularly. Before going into computers, I worked as an auto/RV/marine mechanic for fifteen years (and it is still my hobby), and one thing I have learned is that metal to metal contact induces wear. Oil helps to prevent this by putting a thin barrier between moving metal parts. I would think that the same would apply to a guitar and fret/string contact. I do use flat wounds on my electric, so that can explain the barely noticable wear after 20 years of use by me (which I dressed up while I had it apart to put in my new SD's!). Though the same is for my twelve string, which has rounds on it (I do play it about half as often though), which I would think could induce more fret wear.
Either way, I am happy with my care method!