My F250 has the simplest factory "oil cooler" of all - - - one piece of of 3/8" steel tube, bent in a 180 and follows the contour of the front crossmember. No extra fins, just plain ol' tube. Cheap and really easy to make.
Good question, in a high flow situation like that.The cooler is about 3 inches square. I really don't see how something that little is really doing very much.