Kay,
It has been suggested to add a little squirt/few drops of quality dish detergent to the water flush. It cuts grease like on china plates and cleans up the inside of the hoses and engine. If it was serious, you may have to remove the radiator hoses and clean the inside of the hoses with rags and flush the radiator by itself. DO NOT use a HD comercial radiator flush as it will cause more hose connection leaks and radiator leaks.
Good luck, Usually the first time you do the oil cooler seals is just practice
.
John_AZ