Mere water or washing powder won’t do the trick of removing the oil stains from concrete. However, you can initially wash and clean the surface to remove excess oil on the surface which has not being absorbed as yet.
You will need some sawdust for removing the oil stain from concrete. Pour sawdust upon the stained surface and make sure to cover up the entire tinted portion with a heap of sawdust.
Let the sawdust absorb oil from the concrete surface and wait for at least 30 minutes.
Take a broom and dustpan and sweep away the soiled sawdust completely. You won’t need that sawdust anymore and you can discard it.
You will need to spray water onto the stained surface using a hose. Be sure to thoroughly wet the entire blemished area but not to create a puddle of water over it.
Take some powdered laundry detergent and sprinkle it over the wet surface. Cover the entire blotted area with detergent and then start scrubbing it to make soap suds. Once you see soap suds are formed, stop for a while and let them dry onto the concrete floor. When the soap suds will absorb into the concrete, they will emulsify and push out the oil molecules towards the surface, allowing you to remove them comprehensively.
Take your broom and dustpan to clean up the dried soap solution from the stained surface. You will have to rinse the concrete surface once again to wash away any remaining soap on it. Let the floor dry overnight.