I'd like to see some hard data on these too. I find it hard to believe that it would have much effect on oil temps...
Then again, many find it hard to believe that the radiator tank mounted cooler in the Impala SS has much effect, but when documented, the cooler reduced temps by 40F vs no cooler(peak 230F vs 270F), which is the same as the oil to air cooler does for the taxi and cop cars.