Personal mechanic serviced the car by changing the oil. When checking the coolant in the radiator he discovered an oil residue on top of the coolant and the radiator cap. Took the car to Jeep dealer service department. Was told nothing was wrong with the car and that what was occurring was a characteristic of the vehicle!!! Personal mechanic feels the transmission cooler attached to the radiator has got a crack and the oil is seeping into the radiator.