If the oil stains are fresh, the thing to do is to soak up the surplus oil with either sand, clean cloth, kitchen tissue (making sure that you do not spread the oil and further stain the concrete) or kitty litter. In fact, any absorbent material will do provided that it does not react with oil. As soon as all the surplus oil is soaked up, clean the concrete with either a solvent like mineral turpentine, or a proprietary brand of degreaser. Make sure that you follow the manufacturer instructions when using any brand of degreaser. Paint stripper is also a useful aid in getting rid of fresh oil stains.
Concrete is very much like a big sponge. When oil is spilt it tends to soak very quickly into the concrete and so the longer you leave oil on a concrete surface, the harder it will be to clean up. One method that has proved useful in the past has been to use engine degreasers on the stains. Spray or coat the degreaser onto the surface, leave for a short time (depends on the product, you must read the instructions) and then hose off with as much pressure as your garden hose will give. It may be necessary to repeat this process a few times and sometimes if the stain is quite old, the best result that you can hope for is a paler stain than you started with!
Another method to remove oil stains is to make a poultice of two parts lime and one part mineral turpentine. You will also need a plastic supermarket bag. Simply mix the turps and lime into a thick paste (use rubber gloves and take the usual safety precautions that you would when using any chemicals), spread over the stain and cover with the plastic bag. Leave it for about eight hours. Remove and repeat if required.
Sometimes careful spot bleaching of stains will have a dramatic stain removal effect but make sure that the bleach you use stays only on the oil stain otherwise it will lighten the colour of the surrounding concrete and make the oil stain stand out as badly as before.
I have also known really house-proud people who will chip out the surface of stained concrete and make a paste of fresh mortar to fill up the hole. This is very extreme! The best way is to prevent the stain happening in the first place. Use drip trays under cars that park either in your garage or on the driveway.
or use Griot's Garage Oil and Grease Cleaner
According to Griot's, the oil and grease cleaner actually contains oil-devouring microbes. All you have to do is keep the cleaner wet, and the microbes will turn the oil into harmless compounds that you then just rinse away. Griot's says the product has a variety of applications beyond concrete cleaning, including cleaning the engine compartment of your car - and even removing oil and grease from your clothing.
or
Look for a new product from the people at Quikrete. They're known, of course, for the little yellow bags of concrete you can mix and use to install a post for a basketball net - or put down a new walkway. Quikrete's latest product is a concrete resurfacer. You mix it up and apply it with a squeegee and get a finish that looks brand new.
hth, steve
