About 25 degrees Celsius ambient, ~3000 - 3500 rpms, slow speed (not much airflow). Steep climb, pulling a 2000 pound load, with family of four (+ dog), and related gear for a 3 week road trip. I was surprised to see the temp gauge climb past half way and reach 3/4. Had the scan gauge plugged in for the trip. Interesting stuff learned about coolant temp, ignition timing, load and intake air temps.