Coolent

Coolant doesn't change color unless something is wrong such as engine oil getting into it. A lot of GM cars came with Dex-Cool which is red. We call it Dex-Mud. My opinion is get that c rap out of there. GM advertised it as "lifetime" coolant. Later, after you buy the car, it specifies in the owner's manual to change it every two years like all other cars. Coolant is alcohol and that's not going to change. The reason for replacing it is the water pump lubricant and anti-corrosion additives wear out in about two years and acids build up in it from the normal seepage of combustion gases that get into it. Even the Dex-Cool company recommends replacing it every three years. They never expected it to be lifetime coolant.