So I got a new radiator now. However, overheating still persists. It takes a little longer now, about 15-20 minutes on the freeway, but in after that (or after about 10 minutes in heavy traffic), the temperature needle starts heading for the 3/4 mark again.
Any other ideas what this could be? Is it completely impossible that this could be happening due to the different oil it's running now? I'm just asking because BEFORE the oil change, I did not have any overheating problems, and I even drove the car on a slightly longer trip than just to work.