The issue you had with the Oil can also be a form of level-scaling. It's another one of those aspects of the game that appears entirely random, and can easily be 'argued' to be entirely random, but on closer inspection quite clearly has some 'background algorithm' effecting it.
I experimented on a large map when I was bored at an end-game scenario whereby I tried to keep all other civs alive while maintaining none of them posed any real threat to me. Alongside the hilarity of the AI always needing to declare war on me, no matter the absurdity of the situation, it also exposed the resources level-scaling, as each time I managed to secure 100% ownership of all the Uranium it would 'exhaust' one of my deposits and magically respawn another Uranium deposit inside AI territory, no matter how small and ludicrous they were.