Ron Kirn has said if you must oil just get mineral oil at the drug store. Lemon oil is full of all kinds of stuff other than lemon and oil. I have used Fret Dr for years with good results but I only use it maybe if I get a new guitar with a light board and then only a tiny tiny bit. Usually I never treat them again. Some guys slather it on a few times a year and it can leach under the frets etc. Regarding the Fret Dr, it dawned on me after a few years that I have no idea what is in the "secret formula". I'm still using it on the very rare occasion, if it ever runs out I'd just get bore oil or drug store mineral oil.