ideally the amount used is almost negligible, and buffing removes most of the residual, it's not soaking the wood until saturation.
the furniture folks say " raw linseed oil or teak oil for rosewood is the best bet . No petro based. Once or twice a year, apply oil to your rosewood pieces to gently restore them to like-new condition. Using a soft, clean cloth, apply a little quantity of oil to the surface, working with the grain of the wood" One of the folks I've worked with contends that coconut oil is the closest to humans natural and I can tell you from many years of woodworking that just hand rubbing a finish .. literally... can make it shine ... of course this on non lacquered woods.
When I bought my PS acoustic, I thought whatever they treated the fretboard with was excellent stuff, because it looked and felt great. So I asked about it.
I was told
boiled linseed oil was used as one of the steps. The word, 'boiled' was stressed.
Unfortunately, I don't remember what they sealed it with after wiping it off - there was something mentioned in the conversation, but my fretboard never needed treatment, and I plain forgot.
The reason I remember the boiled linseed oil is that my brother uses it when mixing his own oil paints, like the Old Masters did, and I recalled him talking about his ingredients, and thinking that paintings made with that kind of oil paint have lasted a very long time, indeed. So that seems like a pretty good bet.
As an aside, his paintings are pretty amazing if you haven't seen them, you owe it to yourself:
www.robertschefman.com
I’m not plugging his work, I’m just proud of him for being masterful. I've never mastered an art form, and it amazes me when someone's great at something. Here’s one of his oil paintings:
Of course, raw and boiled linseed oils are two different products.
There you have the full extent of my knowledge about linseed oil. other than flax seed (which is linseed) is good for digestion and thought to aid in reducing heart disease and diabetes.
Here's my thinking about oils and other products to use on guitars:
The guitars I have were hella expensive. I'd rather err on the side of 'not controversial'. Just the way I roll.