Removing stains from your concrete:

Depending on the type of concrete you have most instances you can remove any stain from your concrete surface

Drive ways are the most common areas that need cleaning  due to oil spills and fuel spills if you have a plain finish drive way you can by a product call hydrochloric acid

It mixes to the strength you need but seek professional advise first

It's quite simple to apply by spray bottle that's what I use and spray on affected area and scrub with a tough brush then hose off

If it has not removed all that you want removed start process again

Read bottle for instructions and keep away from bare skin

If you have a coloured drive way , Or it's  being exposed aggregate

Or stenciled colour Hydrochloric acid on coloured surfaces is not ideal for your self to do , if mixture of acid it's to strong it will remove colour from that area you have chosen , so seek advice from a proff

On exposed aggregate areas most of the time they have a sealer applied  so if so the stains will be superficial so the acid to water ratio will be small

Even if you damage the surface of your concrete either being exposed aggregate or coloured concrete most of the time it can be repaired

Don't forget though colour is very hard to match if your concrete is old