Felix. I had a simular experience a long time ago and flushed it out with naptha, which is lighter fluid. B carefull not to rub on the spot just flush it out. Naptha is a light cleaner for chemical spills. The other things you tried won't effect it because your trying to mix oil ( chemical ) and water. One normally won't clean the other unless it has a degreaser in it. Gasoline has oil in it but naptha doesn't. You can buy it at Home Depot and i'm sure at other places like that in the paint section. It will take the oil out of the bumper. Then you will have to let air dry then apply armor-all.If you don't see any damage on the bumper, then mother nature will take care of it in a few day's with just plain weathering. John