A fascinating discussion chaps. I have been using oils for years but learnt some things from this discussion.
May I add that I use oils because of their capabilities for wet blending. In so doing the accurately derived colour created won't really exist in any great detail as the shadows and highlights will alter it from this "starting colour", they are purely analogue in the blends between them.

I think too much thought is going in here re oils ,they are not like acrylics they work best by experiment with some knowledge as with what works with what.
Noted here that most advocate wet on wet mixing apart from Ron C whow has a different approach .I have been painting in oils since the early seventies and was a great champion of the wet on wet no additive school but things have changed " been listening to Bob Dylan too much"

I now prefer the wet on dry school of thought with thinned paint shown to me by David Mitchell ; and given his superb work you cant get better.
It takes a bit of practise but the results are great and you don't lose the fade out as the paint dries super fast " well as oils go"

I like entering competitions and given the preference these days for acrylics the wet on dry oils is the better method for competing against the acrylic guys