Right after I installed, the weather turned cooler, so I don't have any tests with 90+ air temps, but I did run a test where I put the A/C on full blast and drove about 25 minutes. Outside temps were around 80. I know with the old radiator that coolant temps would have easily gone into the high 180's or 190's. With the new radiator, they stayed fixed at 180-183. My t-stat is 180, and my fan turn-on temps are 185.