GM used the red Dex-Cool, (Dex-Mud) and advertised it as "lifetime" coolant to make their cost of maintenance appear to be lower than that of their competitors, but on the vehicle there's a sticker that says to replace it every three years. Even the Dex-Cool company doesn't want you to go three years. They recommend every two years just like for all other brands of antifreeze. The antifreeze is alcohol and will always be alcohol. It's the additives like water pump lubricant and corrosion inhibitors that wear out, then the acids that normally form in the system begin attacking metal parts. That's why GM owners have so many problems with corroded and leaking heater cores and radiators.
A lot of mechanics want to get the Dex-Cool flushed out and replaced with a different brand of antifreeze, but that is only done when it's time for a flush or a repair. When you're just adding to top off the reservoir, stick with what is in there now. There are actually about a dozen different antifreeze formulas now as each car manufacturer is trying to address their individual problems. There are also some brands of antifreeze that claim to be universal and can be mixed with any other brand. I don't know how true that is or whether I'd want to believe the salespeople, so unless Saturntech9 has a better answer, I'd stick with the Dex-Cool unless it's past time for flushing the system. The "Dex-Mud" comment refers to what a lot of people called the coolant, and what it turned into when mixed with an incompatible brand of antifreeze. That's why I'm leery of adding some other brand of antifreeze to what you have.
Monday, September 19th, 2016 AT 3:18 PM