Asphalt and concrete can be marred by many things. Leaves that aren’t removed promptly can leave long-lasting outlines on the surface. Water can stain it, particularly if the water source has heavy iron content. However, one of the most difficult stains to deal with is from oil, and petroleum products in general. If you don't clean them up before sealcoating, you risk having them seep through. You can clean up fast and perfectly with the right oil stain remover.