David, from what I understand the
oil I in radiator's chief advantage's are that it gets the
oil warm quickly and thermal transfer is more efficient. That being said, the
oil needs to stabilize at a higher temp than the water does and would require an oil thermostat. I even did this with my separate oil cooler and it (canton) works very well. This does make plumbing more complex but you get the advantages without much draw back.
Steve