So, no stop and go traffic, good airflow over the rad. Rad is new, so not likely plugged. It is running hot, but not to Chernobyl levels. Minor loss of coolant over time, but no noticeable oil in coolant or coolant in the oil. Final test for coolant in oil - remove the oil fill cap and test taste the condensate on the inside of the cap. If it is sweet, there is coolant in the oil. I am leaning toward a bad cap. Some parts stores can pressure test it for you before you buy a replacement that may not be needed.