Some people have used Coke Cola. Ya, I know that sounds wrong, but it does work in some rare cases.
The thing you need if the oil is impregnated is heat and lots of it.
We have removed the stain complete and in some cases have not removed it, but made it so much better, that there is a faint remembrance of the dark oil stain. For this reason, hot summer days are always the best time to remove them.
Also, if doing a drive way, one must be aware of their local discharge laws. Some states may consider the street/ gutter as US water ways.
If you would like to know more, you can visit the NEW PWNA website coming out later next week. Each and every member will have a searchable web page to help their ranking on Google search engines. We will also have the first COMPLETE EPA section that address the water run off issues for each state, including the EPA links as well...
(Magazine article was removed).
If you want to learn more, give me a call at 510-612-0437