1. Scout opens all Oil before 3000 BC
Maybe I'm missing something (so please enlighten me), but I thought that you still needed to tech to Combustion or Plastics before you connect-up the Oil.
By that point in the game, I'll almost always have Oil within my borders--since getting that far in the tech tree means that I am playing for a Space Victory and I tend to grab a lot of land in my Space games.
So, what's the big deal about knowing where Oil is located if you still can't harvest it? Sure, you could put a Fort on it in preparation for learning Combustion, but you could do the same if you'd researched Scientific Method first.
Or is the point that you can delay researching the tech-rate killing Scientific Method tech and still know where your Oil is? Okay, let's say that this point is the case... will you be able to build any units which require Oil without first researching Scientific Method? I can't say that the situation has come up for me, but I let's think about if it is possible... Flight requires Physics, which requires Scientific Method... Industrialism requires Electricity, which requires Scientific Method... I suppose that Combustion itself enables Destroyers and Transports and Combustion can be researched prior to learning Scientific Method...
So, yes, there's at least one use: you can rule the seas with an Oil-based navy without needing to research Scientific Method. Are there any other important benefits? +1 Hammer per Oil square (if you even bother to settle with any of them in your fat crosses)? Anything else?