Parts for your 2020 Holden Commodore-Head gasket

2020 Holden Commodore head gasket: what it does, how to look after it, and when to replace

Technical sources confirm the 2020 Holden Commodore (ZB) uses a conventional cylinder head gasket. GM Global Service Information (GSI) for the ZB Commodore’s 2.0L turbo petrol (LTG) and 3.6L V6 (LGX) details cylinder head removal/installation with a replace-once multi‑layer steel (MLS) head gasket and torque‑to‑yield head bolts. The Holden/ACDelco parts catalogue likewise lists a head gasket for these engines, and the Opel Insignia B workshop manual (the platform twin) specifies the same MLS gasket approach. So, the head gasket is absolutely relevant on this model.

On a 2020 Commodore, the head gasket’s job is to seal the combustion chambers while keeping engine oil and coolant in their own passages. The factory MLS design handles high cylinder pressures (especially on the 2.0T) and heat cycles, provided the cooling system is healthy and the engine isn’t overheated.

It’s not a scheduled service item. Instead, look after the cooling system and it’ll usually last the life of the engine. Stick with the correct long‑life OAT coolant (Dex‑Cool type), maintain the proper 50/50 mix, and change it at the intervals in the service schedule. Keep an eye out for coolant leaks, a tired radiator cap, lazy fans, or a sticky thermostat—any of these can cause overheating, which is the main head‑gasket killer.

If a head gasket does need replacing, it’s a precision job best left to a trained tech. The procedure in GSI calls for new torque‑to‑yield head bolts, correct cleaning of block and head surfaces, and exact torque‑angle sequences. The V6 has two cylinder heads, so both sides are typically assessed, the head(s) may need to be checked for flatness and resurfaced if out of spec. It’s smart practice to pressure‑test the cooling system afterwards, change the engine oil and coolant, bleed air properly, and recheck for combustion gases with a chemical test. Done right, an OEM‑quality MLS gasket will seal reliably for heaps of kilometres.

• Common warning signs: unexplained coolant loss, overheating, white exhaust steam, rough cold start or a misfire, pressurised hoses when cold, or milky contamination under the oil cap.
• Prevention tips: fix leaks promptly, don’t ignore a creeping temp gauge, and avoid hard driving if the car’s running hot.

Popular questions about 2020 Holden Commodore head gaskets

Does the 2020 Holden Commodore have a head gasket?
Yes. Both the 2.0L turbo four and the 3.6L V6 use a multi‑layer steel head gasket, as outlined in GM Global Service Information and supported by Holden/ACDelco parts listings. It’s a single‑use item replaced whenever the cylinder head is removed.

What are the classic signs of a blown head gasket on this model?
Typical clues include overheating, coolant loss with no obvious leak, white steam from the exhaust, a sweet smell from the tailpipe, rough running on start‑up, or creamy/milky residue under the oil cap. A cooling‑system pressure test and a combustion‑gas (block) test help confirm the diagnosis.

Is a head gasket a regular service item on the ZB Commodore?
No. There’s no routine replacement interval. Focus on cooling‑system maintenance—fresh long‑life coolant at the specified interval, leak repairs, and good airflow through the radiator. If a head gasket fails or the head is removed for other work, the gasket and head bolts must be renewed and torqued exactly to spec.