Mazda 6 Radiator: Specs, Fitment & Common Faults

On the Mazda 6, the coolant reservoir genuinely differs by turbo vs non-turbo and even build location — always verify against your VIN.

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OEM Part Number: confirm via VIN — radiators (aftermarket) Nissens 68539 / Denso DRM44048

Accuracy note: Covers the Mazda 6 (GJ 2012-) as listed in the UK aftermarket catalogues. Radiators are sold by engine, gearbox and air-conditioning fitment, and one model usually has two or three different cores — a thicker core for diesels and automatics, a thinner one for small petrols — with different hose positions, so a radiator for the wrong engine will not connect up. The references below are UK aftermarket listings whose fitment lists name this generation, labelled by brand with the core size in mm; genuine numbers are those quoted against the listing. Check your engine code and whether the car has air conditioning against your VIN, and replace the coolant and bleed the system after fitting.

Radiators (aftermarket)	Nissens 68539 (375 x 733 x 16 mm, aluminium soldered core, plastic tanks, 2.0 Skyactiv-G 145/165 PS and 2.5 Skyactiv-G 192/194 PS petrol); Denso DRM44048; NRF 550012; Van Wezel 27002280; Hella 8MK 366 308-621; Kale 347925. Nissens 68537 (375 x 733 x 26 mm, aluminium soldered core, plastic tanks, 2.2 Skyactiv-D diesel 150/175 PS); Denso DRM44044; NRF 550151
Core sizes & variants	All GJ radiators share a 375 x 733 mm face. Petrol cars take a 16 mm single-row core; the 2.2 diesel takes a 26 mm core. Two diesel references exist with different Mazda numbers (SH05 and SH06 prefixes) that differ in the fittings supplied, so match the OE number on the old radiator or order by VIN.
Genuine (OE) numbers quoted	PE1115200, PE1115200A, PE1115200B, PE1615200 (petrol); SH0515200, SH0515200A (68536); SH0615200, SH0615200A (68537)
Fitment notes	Inlet and outlet are 33 mm on all three. The petrol unit comes with a filler cap and seals; both diesel units are listed with an expansion tank, thermostat, cap and seals, and 68537 also includes an oil cooler.

Accuracy note: genuinely worth knowing: whether a 6 has air conditioning or a larger optional engine can change radiator sizing on some variants — fitment guides that only ask for model and year can still get this wrong, so cross-check the engine code where possible.

A Genuinely Important Fitment Warning Worth Knowing Before Ordering — Mazda 6 Radiator

If you're replacing the coolant reservoir specifically, this is genuinely worth knowing: fitment is considerably more complex than it might first appear, with real differences depending on whether your engine is turbocharged or non-turbo, and even on which factory the car was built in. Always verify against your specific VIN and visually match the part before buying.

A genuinely specific diagnostic detail worth knowing if chasing a subtle thermostat housing leak: rather than an obvious crack across the housing itself, a failing gasket or seal commonly manifests as weeping specifically around one of the housing bolts — worth checking this precise spot closely before assuming the housing itself needs replacing.

It's also worth knowing that a coolant bypass pipe near the thermostat housing on some Mazda diesel engines has been documented deteriorating with age and heat cycles, worth checking if you have an older diesel model experiencing unexplained coolant loss.

Mazda 6 Radiator: The Part That Keeps Everything Else From Cooking

Few parts get less attention than this one, but on the Mazda 6, a neglected cooling system is behind the vast majority of avoidable serious engine failures. Noticing the early warning signs costs nothing and can save a genuinely large repair bill down the line.

Mazda 6 Radiator: Watch: Replacing It

🎬 Watch: How to Replace Radiator 2014-2021 Mazda 6

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1A Auto step-by-step on the GJ/GL; _HFgbuDLhUU is an alternative that avoids disturbing the A/C.

Before you buy: radiator size and design vary significantly by engine size, transmission type, and whether your car has air conditioning. Always confirm against your VIN before ordering.

Mazda 6 Radiator: What It Does

On the Mazda 6, coolant runs through the radiator to shed engine heat into the airflow, keeping temperatures in check. On many automatics, a separate internal circuit inside the same unit also cools the transmission fluid — one more reason a mismatched part number causes more than just a cooling problem.

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Mazda 6 Radiator: Faults, DIY Difficulty & Aftermarket Advice

These are the same regardless of make or model — see our full Radiator Guide for the three common failure modes, confirming fitment against your VIN, and OEM vs aftermarket guidance.

More Mazda Radiator

The same part, covered across other Mazda models.