Don your protective gear before mixing up the TSP compound. That includes goggles, gloves, and long sleeves. Then, combine one cup of TSP powder with one gallon of warm water, stirring well to remove any clumps. Pour this solution over the oil stain and allow it to sit for around 30 minutes. This should be enough time for the absorbent TSP mixture to draw the oil up and out of the concrete. Then you simply scrub it away with a bristle brush to remove. However, if the stain persists, try adding an absorbent material into the original TSP mixture, such as baby powder or talcum powder. This will give you a paste consistency that can be spread onto the area and left until dry. The oil stain should fade away after the paste is scraped off and disposed of, thanks to the absorbent material safely incorporating it as the oil lifts out of the concrete.