Antifreeze for Honda Insight
The Insight is a hybrid, and that means one practical difference: it has two independent cooling systems. One cools the engine, the other the inverter and power control unit. Honda specifies blue Type 2 fluid for both.
Photographs come from the manufacturer's official materials.
Cooling system volume (litres) engine roughly four to five litres, plus a separate inverter circuit
Why the inverter circuit is the more sensitive one
The passages in an inverter heat exchanger are far narrower than those in an engine radiator. A deposit that would go unnoticed for years in the engine system immediately impedes heat transfer here.
An overheating inverter first limits power and then throws a fault. Replacing one is among the most expensive hybrid repairs there is, far more expensive than changing the fluid in both systems several times over.
Three properties of Zerex Asian Blue speak directly to this: silicon under 10 ppm where the JIS limit allows 250, a phosphate package that works against deposits and scale, and hard-water compatibility.
Who should change the inverter fluid
Honda directs owners to have the inverter circuit serviced by a dealer, and the reason is technical: this circuit has its own bleeding procedure, and on some models it requires forcing the pump to run with a diagnostic tool. An air pocket left in the system produces exactly the effect you were trying to avoid.
Our advice is straightforward: buy the fluid from us and have the work done by a mechanic experienced with hybrids.