What you're probably seeing is the red-colored Dex-Cool antifreeze. In fact, we call that stuff "Dex-Mud" because that's what it turns into. GM advertised that as "lifetime" antifreeze to make their cost of maintenance appear to be lower than that of their competitors, but then on the coolant reservoirs they put a sticker that says to replace it every three years. Even the Dex-Cool company doesn't say it's lifetime coolant.
The place to start is by having the cooling system flushed and refilled. That should be done every two years anyway. One reason is it is normal for acids to build up in cooling systems and you want to get that out. The second reason is the additives wear out in about two years. Those additives include corrosion inhibitors and water pump lubricant. The acids that will form are a common cause of leaking heater cores and radiators on GM vehicles.
The new coolant may not solve the running-hot issue but it's the place to start. Also look at the cooling fins on the radiator. If you live in an area where they throw a pound of road salt on an ounce of snow in the winter, those cooling fins will corrode away and prevent the radiator from giving up the heat to the air.
Thursday, June 18th, 2015 AT 3:36 PM