I strongly suggest visiting your local Apple Store and let them take a look. If your machine no longer reads disks, it could be that the connector to your HD was dislodged in the fall. I imagine it's possible, but it's very difficult to get oil into the drive mechanism; it's sealed like a tank. The Genius Bar, at the least, will be able to tell you the nature of repair required.
The Superdrive isn't sealed at all; I think Poikkeus thought you were talking about your hard drive. If oil got into the Superdrive, it could very easily have gotten onto the laser lens and made the drive useless. I agree with Poikkeus that a Genius Bar appointment should be the first stop for diagnosis and a cost estimate. If you don't like the news you get there, you can buy and install a replacement drive yourself quite easily. But first make sure you haven't got oil all over the inside of your machine and that the rest of it is working OK. I'd buy here:
Genius Bar booking:
I have a 13" Macbook Pro 5.5 (late 2009). I removed internal DVD and installed an O.W.C. Data doubler bracket that allows a second 2.5" hard drive. I blindly purchaced a new Apple Superdrive USB and it does not work. I pulled an older LG generic usb powered DVD drive hooked it up and OSX 10.7.4 (Lion) found and allows me to use it. iTunes burned an audio cd as a test.