I second that. After changing the reference of 'this' to 'null' on line #47, the code will compile. This is exactly why I wanted the full class code.
Now, I don't have an image called "oil.bmp", but making this change will eliminate the compiler error, and assuming you've initialized the url to the file "oil.bmp" correctly, things should go well.
By the way, the compiler error I got when compiling what you gave was this:
Master.java:47: cannot resolve symbol
symbol : method drawImage (java.awt.image.BufferedImage,int,int,Master)
location: class java.awt.Graphics
g.drawImage(oil, 800, 600, this);
This error doesn't mean necessarily that the 'drawImage' method doesn't take BufferedImages as a parameter, what this message means is that there was no 'drawImage' method with a method signature matching the one you provided (in this case, no 'drawImage' method which accepts the type 'Master' as a parameter).