You can get patio cleaners from some DIY stores that will remove oils, but experience says it will be difficult. Using washing up liquid and brushing vigorously will help, and the stain will fade in time.
Do you have any spare blocks? You could replace the marked ones.
DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!