Originally Posted by TundraMan
I used tru-oil on a fretted maple fingerboard on a guitar that I built for a touring musician. He played that guitar for several hours every day. Six months later it looked terrible. The finish had worn away and been replaced with dark gray stains in all the spots he used most often. Similar to what a 50's maple board Fender looks like after 60 years of heavy use, but this happened in a fraction of the time.
In his case, he loved the aged road-worn look so he was perfectly happy with it. However if you're not into that sort of thing I wouldn't use tru-oil on a fretboard, especially fretless.
Ok, that answers that question.
BTW, I did use search but didn't find anything specific on this question, which is what I was looking for.