Ken - how are you measuring your
oil temp? If it is via your dash guage then be prepared to accept that the guage can be up to 20% out.
If you want a proper check on your
oil temps, use an electronic thermocouple-type thermometer, and clamp the thermocouple tip (cable tie works OK) onto the "out" pipe to your cooler, then the "in" pipe from the cooler in turn. Then you will have proper readings of the
oil temps on both flow and return lines on the cooler.
If you want to get really swanky, there are electronic meters out there where you can plug in two or more thermocouples - and switch between them or show the delta between them.
I did this, and now realise that my (mechanical) dash guage reads 10 degrees C low. Once you know the correction factor, all OK, but I would not start to even try to modify the oil cooling system on my car without proper temp measurements first.
HTH