What is the best thing for removing oil stains on driveways?
Scrub with solvent cleaner such as Jizer or Gunk (from Halfords). Then use a strong degreasing detergent such as Janitol or Sugar Soap in hot water to remove the dissolved oil and finally hose off. You may need to do it several times (let it dry out between each go) and you may not remove it completely but it will be greatly reduced.