Some antifreeze can be mixed with other antifreeze, such as types that use propylene glycol or ethylene glycol bases. Mixing different colors of antifreeze, however, can cause corrosion and cooling-system malfunctions if the corrosion inhibitors are not compatible with each other.
Conventional antifreeze and extended-life antifreeze cannot be mixed together, as this causes the antifreeze to become cloudy and lose the extended-life properties. Hybrid antifreeze can be mixed with both conventional and extended-life antifreeze, and it has effective corrosion protection and a long lifespan. Different types of antifreeze can often be identified by their color; for example, extended life is usually orange, and hybrid is usually yellow.