Originally Posted by TommyC
What would you define as high RPMs for extended periods? Are we talking 3.5K for 30 minutes would justify an engine cooler, or redlining for hours on end?
Just running up to red line through the gears should not be a problem. In most cars, it takes a few minutes of sustained high R's for the oil temp to climb toward the danger zone. So, you usually see engine oil coolers in applications like police cars, hipo cars/trucks and in vehicles with high trailer tow ratings.
The 5.0 Explorer engine has a factory oil-to-coolant heat exchanger similar to the one Rich described above, probably to satisfy trailer tow test requirements. I doubt that my truck really needs it though.