Street driving with my 4500 8" and a "normal" sized stacked plate cooler temp is never a concern. I have seen 200 degrees one time and it was in a massive 5 lane traffic jam that was idle speed and crawling for almost 2 hours. Everything was hot at that moment. Engine 210, trans 200, fuel 135, angry fuel pumps, and and angry passengers lol but we made it.

That is with the temp sensor in the pan. If you really want to terrify yourself put the sensor in the hot line going to the cooler....yikes lol.