As the temperatures here in Utah have hit well over 100 degrees for the past couple days, my GL-10 has started having trouble keeping its temp down. I've been very cautious and kept a close eye on the temp gauge on the dash to make sure it doesn't overheat. I've found that it stays cool just fine even at highway speeds without the a/c on, but with the A/C, the temp goes up fast and I have to turn it off again to keep the car cool. Does this indicate that I need a new radiator? Is there something I can do to get it to keep cool even with the A/C or is this just how it goes with an '87? I'm gonna flush the fluid one more time and see if that helps. any recommended brands for coolant?