Parts for your 2020 Holden Commodore-Radiator

2020 Holden Commodore radiator — purpose, care, and replacement

A radiator is absolutely fitted to the 2020 Holden Commodore (ZB). Technical references that specify the liquid-cooled system include the Holden ZB Commodore Owner’s Manual (2020), GM Global Service Information (GSI) for the Opel Insignia B/Commodore ZB platform, and ACDelco/GM cooling system specifications for Dex‑Cool long‑life coolant. These documents describe an aluminium cross‑flow radiator with electric cooling fans and a pressurised expansion tank used across the 2.0‑litre turbo petrol, 2.0‑litre turbo‑diesel, and 3.6‑litre V6 AWD variants.

The radiator’s job is simple but vital: it sheds engine heat so the Commodore runs at the right temperature, protecting the head gasket, turbo (where fitted), and plastics. Hot coolant leaves the engine, flows through the radiator’s fine tubes and fins, and dumps heat to oncoming air and the twin fans. GM’s OAT (Dex‑Cool) coolant raises the boiling point, guards against corrosion in alloy components, and keeps the water pump lubricated.

As part of routine servicing, keeping the radiator and cooling system in top nick pays off with stable temps and longer engine life. Recommended practices include:

• Coolant service: replace Dex‑Cool long‑life coolant about every 5 years or up to 240,000 km (whichever comes first), or sooner if tests show contamination.
• Mix and quality: refill with the correct OAT coolant that meets GM Dex‑Cool spec, use demineralised water for a 50/50 mix unless pre‑mixed.
• Inspection: check for damp spots, orange crust at end tanks, soft or swollen hoses, fan shroud damage, and a tired pressure cap.
• Cleanliness: keep fins clear of bugs and road grime, blow from the engine side out with low air pressure to avoid bending fins.
• Temperature control: verify fans cycle on with A/C and at operating temp, investigate any creeping gauge or coolant smell promptly.

When replacing the radiator, only work with a cold engine. Depressurise via the cap, drain at the lower hose, swap the unit with new seals, and refill slowly while bleeding at the designated points. Run the heater full‑hot during the bleed, top up the expansion tank to the mark, and confirm no leaks or air pockets. On the 2.0T and V6, it’s smart to inspect the thermostat and water pump at the same time, as access is already open.

If overheating, a low coolant warning, or steam appears, stop driving to avoid head gasket damage. Towing is cheaper than an engine rebuild.

Popular questions

What coolant does a 2020 Holden Commodore use?
The ZB Commodore uses an Organic Acid Technology (OAT) long‑life coolant that meets GM’s Dex‑Cool specification. Many quality brands supply a Dex‑Cool‑equivalent in orange. Use the correct spec and mix with demineralised water if not pre‑mixed.

How often should the coolant be changed?
Under normal conditions, plan on about every 5 years or up to 240,000 km. If the vehicle tows, sits in heavy traffic often, or tests show low protection/corrosion inhibitors, service sooner.

Is it safe to drive with a small radiator leak?
It’s risky. Small leaks can worsen quickly, drop system pressure, and cause overheating. Top up only to reach a safe spot, then organise a proper repair or tow to avoid expensive damage.