What does the planet need oil for?

For the last few days I have been contemplating why the planet makes oil. I know that it didn't start producing oil for humans to drill and use and fight over and sell and make fortunes off of. I tried Googling and looking for information about what the planet could possibly need oil for and I am convinced that no one knows and no one cares.
My husband and I believe that the planet does need oil and that everything that is happening and has been happening around the planet is probably directly connected to us drilling and using up all the oil in the planet.
Is the planet like a car engine and needs the oil we are selfishly taking away to run properly, to keep earthquakes, tornadoes, hurricanes and tsunamis under control? Could the increase in temperature, i.e. Global Warming be caused by the rising temperature in the Earth's core due to loss of oil? Does the planet replenish the oil that we are stealing? I am currently under the impression that once an oil well dries up, it is useless and oil will not come from that same source anymore. That is why there is so much hub-bub about drilling in Alaska and off the coast of California, right? Because there are millions of sites around the world that have already been drilled to the point of nothing and now the oil companies need somewhere else to start syphoning the oil out of the planet.
I'd like to know if there is any research on weather the planet needs the oil for anything, like temperature control, I'd like to know if anyone has even thought about this, I would assume Mr. Gore may have given it some thought with his documentary and all, but has anyone ever vested any time into seriously finding out the answer?

Well that is all for now, I am off to Google some more and see if I can find anything about this.