How do i separtate oil(like car oil) from rocks and soil?

I am going a science project on cleaning up oil spills in the ocean......How do i separtate oil(like car oil) from rocks and soil?
For rocks, a high pressure water spray is usually what's used. Soil is a bit more difficult, there are a couple of new technologies out there that are supposed to draw oil out, but even then, not completely. Bioremediation is an option. I remember learning about a spill where they released an oil eating beetle into the environment. But then you have a new problem of invasive species. If you're doing this on a limited scale, then a constant flushing of the soil may work, put it in a strainer %26amp; continuously pour water into it. That somewhat mimics the natural process that beaches are often left to do.