I have an
oil cooler with an automatic thermostat. There are a couple of companies making quality parts.
On the street, I rarely see
oil temps >180*. On the track, it doesn't get much above 210*. Water temps considerably lower, never over 200*.
Unless you're planning on open track time, don't bother. Not worth the expense or hassle. Think of how many trucks are wandering around out there, working hard, and no
oil cooler.