Antifreeze for Subaru
Every Subaru owner eventually hears the words “head gasket”. Two properties of Zerex Asian Blue, the complete absence of silicates and of 2-EHA, speak directly to the two mechanisms that quietly destroy a Subaru cooling system. Subaru is named on Valvoline's official data sheet.
Photographs come from the manufacturer's official materials.
Why a boxer engine is more sensitive than others
In a boxer engine the cylinders lie flat, so the heads sit on the sides of the engine and the head gaskets end up at the lowest point of the system. That means they are permanently submerged in coolant. In a conventional engine the head gasket sits above the coolant level when the car is parked. In a Subaru it never does.
On top of that, both the block and the heads are aluminium. Aluminium corrodes far more readily than cast iron, and only one thing protects it: the inhibitor package in the coolant. When that package is exhausted, nothing is left.
Silicate and the water pump seal
Silicate protects aluminium quickly, but over time it drops out of solution as a gel-like, sandy deposit. That deposit passes over the rotating water-pump seal and slowly grinds it away. This is precisely why Asian manufacturers moved away from silicated coolants.
The JIS K 2234 standard permits up to 250 ppm of silicon. Zerex Asian Blue contains less than 10 ppm, under four per cent of the allowance. Effectively zero.
Why a “universal” coolant is a bad idea here
Many cheap “universal, fits every car” coolants use 2-ethylhexanoic acid (2-EHA) as an inhibitor. 2-EHA is a plasticiser, and its job is precisely to soften plastics and rubber. In a cooling system that means softened gaskets, weeping plastic tanks and a sticky film on the passages.
The Zerex Asian Blue data sheet states it plainly: the product contains no silicates, borates, 2-EHA, amines or nitrites.
What we promise, and what we do not
This is not identical to Subaru's factory Super Coolant, and we will not claim that it is. It is an independent, patented formulation (US 5,454,967) whose official data sheet lists Subaru and which meets ASTM D3306 and JIS K 2234.
If your car currently holds a different fluid, flush the system completely rather than simply topping up. And one more thing: if a head gasket is already leaking, no coolant will repair it. This product is prevention, not repair.