Antifreeze for Subaru Impreza
The Impreza, and especially the turbocharged WRX, sheds far more heat than a naturally aspirated engine. The turbo housing and post-intercooler air add thermal load, while the cooling system stays the same size.
Photographs come from the manufacturer's official materials.
Cooling system volume (litres) roughly six to seven litres
Turbo, cavitation and the water pump
High temperature and high revs together create vapour bubbles behind the water-pump impeller. This is cavitation. Those bubbles collapse against the metal surface and tear microscopic particles away, and over time that eats the pump.
ASTM D2809 measures exactly this: a 100-hour aluminium pump test where 10 means “perfect” and 1 means “perforated”. The limit requires at least 8. Zerex Asian Blue scores 10.
Frequently asked questions
Does a WRX need a special fluid?
The specification is the same, a blue, silicate-free HOAT. On a turbo engine, system cleanliness and timely changes simply matter more.