For nearly a decade, vehicle manufacturers have been introducing and using a variety of extended-life coolants. The only thing these coolants have in common is that they all seem to differ in formulation and color. There are orange coolants, green coolants, blue coolants, red coolants, yellow coolants, even pink ones. The proliferation of different coolant types has created a great deal of "chemical confusion" with motorists and technicians about what type of antifreeze should be used to top off or refill late-model cooling systems.

We're not going to summarize the whole laundry list of OEM coolants and colors here except to say that each vehicle manufacturer has their own unique coolant specifications based on corrosion protection requirements, service life and chemical compatibility. These requirements are usually spelled out in the vehicle's owner's manual, and/or a decal or label on the coolant reservoir. It's important to always use the coolant chemistry recommended in the vehicle owner's manual. For example, Ford and Chrysler specify hybrid OAT-only coolants.

You can't go by the color of the dye in the coolant because two coolants with similar colors may have different chemistry, and two coolants with different colors may have similar chemistry. What's more, colors can change if somebody tops off the system with a different coolant.

The more we get into the specifics of each type of coolant, the more confus...