Concrete must have cured at least 30 days before staining or painting.  Use an oil stain remover such as Seal-Krete OSR to lift stubborn oil stains.

Etch smooth-finished surfaces (basements, garage floors) with a concrete etching solution like Seal-Krete Clean-n-Etch to ensure surface penetration and adhesion. 

This step is important for smooth troweled concrete surfaces such as basement floors; however, it's also recommended for rougher finished surfaces.