I'm not here to tell anyone what to do or not do with their guitar. If it works for you, knock yourself out!
But here is what the experts tell us:
While lemon oil is OK to use -- sparingly is recommended -- on Fender-style maple guitar fretboards, which are manufactured with lacquer or polyurethane sealants, it is NOT recommended for open-pore (unsealed) guitar fretboards. Citrus-based polishes generally contain waxes, petroleum distillates, emulsifiers / detergents, and water.
Rule of thumb:
--No water (water loosens water-based glues and swells wood, which can cause binding, inlay and other trim to come loose)
--No citrus-based products (these are solvents; they can soften the wood, and they can affect the glue around bindings and inlay)
--No silicone (it impregnates wood, builds up and is hard to get out of wood; it's also bad for the finished parts of your guitar and is best avoided altogether)
--No waxes (wax may make the fingerboard shiny, but it does so by adding gunk to the fingerboard, which also makes it tacky / sticky)
While using any of this stuff is frowned upon, the VERY occasional and sparing use of it -- once a year or once every couple years -- is probably not going to ruin your guitar.
But constant use, frequent use, or over use, is likely to eventually have a deleterious effect.
One other thing: when using 0000 steel wool, I lay down a 2" piece of low-tack tape to both sides the guitar top next to the fingerboard extension. While it's virtually impossible to scratch the fretboard with 0000 steel wool -- it turns to powder -- it will scratch the glossy finish of a guitar. When using it on the fingerboard extension, you want to be careful not to accidentally let it come in contact with the finish. The tape prevents accidents.
Glenn