First you should find out how the oil got in there to start with and fix the problem.
Oil will float on water so you can get most of it out by just adding water (coolant?) and letting the oil float to the top so you can remove it, perhaps with a turkey baster?
There are also commercial products that will help dissolve or flush away oil in radiators.
Last resort: Have radiator removed from car and steam cleaned.
Oil will float on water so you can get most of it out by just adding water (coolant?) and letting the oil float to the top so you can remove it, perhaps with a turkey baster?
There are also commercial products that will help dissolve or flush away oil in radiators.
Last resort: Have radiator removed from car and steam cleaned.