The oil that we drill for and pump out of the ground to use for gasoline and other fuels is around 3,000 to 6,000 feet deep in the earth.
However there may still be several billions of gallons of crude oil even deeper in the earth as in 10,000 to 40,000 feet in the earth.
However we have not had to drill that far down into the earth as of now.
The oil that is in the ground is made of fossils of millions of years ago.
The oil was made from dinosaur bones, human bones and other animal bones that decayed all those years ago and then turned into oil.
Oil is usually found at least 3,000 to 6,000 feet deep in the ground although when oil was first discovered it was closer to the surface of the earth.
But now that we've used oil for at least 100 years the oil we get now is deeper in the ground but we are still able to extract billions of barrels of crude oil everyday.
We will maybe run out of gasoline and crude oil eventually but not likely for another 100 or 300 years which is a long time.
Now with ethanol being added to gasoline that makes the gasoline last longer.
Oil is derived from fossils of dinosaurs and other animals including humans of years past which is why oil is referred to as fossil fuels.
We may also never run out of gasoline or oil ever as long as more oil is naturally being made in the ground and we still have several billions of gallons of crude oil available underground.