Originally Posted by Pharmacist

I woud imagine a direct to air cooler would be better since it dumps the heat straight into the atmosphere as opposed to overloading the cooling system. Besides, you can get a larger surface area via a direct to air cooler as opposed to using the radiator's already existing area to vent more heat. Not to mention that cooling will be quicker due to greater temp differential between oil and air than between oil and radiator coolant.