Author Topic: MK8 GTi coolant warning light  (Read 669 times)

Offline BingVW

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MK8 GTi coolant warning light
« on: 09 August 2026, 10:24 »
Hi all,

Last night had the coolant warning red light come on just outside the house, never smelled any coolant or seen any leaks, checked the level and yes it looks low (on a hot car).  Can I top it up with something like this for now or does it have to go to VW as mrs needs the car for work.

https://www.halfords.com/motoring/engine-oils-and-fluids/antifreeze/halfords-advanced-g65-antifreeze-and-coolant-concentrate-2l-448195.html?isVrnSearch=true

Any recommendations
Mk2 16v GTi - Past
Mk2 VR6 transplant - Past
Mk8 GTi  Moonstone grey- Current
997 Turbo manual - Cobolt Blue- Current

Offline Watts

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Re: MK8 GTi coolant warning light
« Reply #1 on: 09 August 2026, 10:55 »
I would only top up with the correct coolant. There's a chance that the coolant has settled (air lock cleared) rather than there being a leak so it may not need changing which it might if you've put the wrong coolant in. Having said that, given you say a mk8 as opposed to an 8.5, if it's a few years old it may well be a leak so might be best to top up correctly and book it in to get it checked.
2025 Oryx Black Edition Clubsport with Performance Pack.
Previously:
2019 Oryx 5dr TCR with Reifnitz.
2015 Tornado Red 3dr GTI PP, manual, Santiagos, Audi short shifter.

Offline SRGTD

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Re: MK8 GTi coolant warning light
« Reply #2 on: 09 August 2026, 10:58 »
I’d not use a generic coolant as it runs the risk of sludge forming in the cooling system that could cause blockages and corrosion of the aluminium parts of the cooling system. It’s also unlikely to be to VW’s spec for coolant.

I’d use G12 Evo ready mixed (pre-diluted) coolant which is the current factory fill coolant used by VW. It’s backwards compatible with the older G12+, G12++ and G13 coolants and meets VW’s spec for coolants, so if your current coolant is one of these or G12 Evo, you’ll be OK to top up with G12 Evo. Your car’s cooling system expansion tank should have the coolant type printed on it that’s been used by VW in your car and / or it should be stated in the owner’s manual).

https://www.coxmotorparts.co.uk/product/vw-shop/volkswagen-g12-evo-coolant-1l-5l/

Edit; once topped up, keep an eye on the coolant level (I check mine as part of my regular checks that I usually do when I clean my car - engine oil, coolant, washer fluid and tyre pressures). If the level does drop again, then as @Watts has suggested, get it checked for possible cooling system leaks or potential water pump / thermostat housing leaks (water pump / thermostat housing leaks were a weak point on previous generation Golfs with the 2.0 EA888 engine; I don’t know if this is still the case with the mk8 / mk8.5).
« Last Edit: 09 August 2026, 11:35 by SRGTD »
2020 Polo GTI Plus; Pure White, DSG (because they all are)
Gone but not forgotten;
2016 Polo GTI; Blue Silk
2011 mk6 Golf GTD; Carbon Grey
2007 mk5 Golf GT (2.0 170bhp TDI version); Deep Black Pearl
2002  mk4 Golf GTI (the 150 bhp diesel version); Deep Black Pearl

Offline BingVW

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Re: MK8 GTi coolant warning light
« Reply #3 on: 09 August 2026, 12:29 »
Thanks guys I will have to try and grab some from VW dealer in the morning.

I don't suppose I can use this

COMMA®
Xstream
G40
Antifreeze & Coolant

CONCENTRATE
Protection down to -52°C*
Glysantin® G40® by BASF is approved by:
Audi/Bentley/Bugatt/Lamborghini/Seat/Skoda/W/Porsche vehicles (TL774-G),
Liebherr (MIN LH-01-COL3A), Cummins (CES 14603), Deutz (DQC CC-14), MAN Truck & Bus (MAN 324 Typ Si-OAT), Mercedes-Benz Cars (MB-Approval 325.6).
Mercedes-Benz Truck & Bus (MB-Approval 325.5), MTU (MTL 5048),
Mk2 16v GTi - Past
Mk2 VR6 transplant - Past
Mk8 GTi  Moonstone grey- Current
997 Turbo manual - Cobolt Blue- Current

Offline SRGTD

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Re: MK8 GTi coolant warning light
« Reply #4 on: 09 August 2026, 13:12 »
Thanks guys I will have to try and grab some from VW dealer in the morning.

I don't suppose I can use this

COMMA®
Xstream
G40
Antifreeze & Coolant

CONCENTRATE
Protection down to -52°C*
Glysantin® G40® by BASF is approved by:
Audi/Bentley/Bugatt/Lamborghini/Seat/Skoda/W/Porsche vehicles (TL774-G),
Liebherr (MIN LH-01-COL3A), Cummins (CES 14603), Deutz (DQC CC-14), MAN Truck & Bus (MAN 324 Typ Si-OAT), Mercedes-Benz Cars (MB-Approval 325.6).
Mercedes-Benz Truck & Bus (MB-Approval 325.5), MTU (MTL 5048),

I don’t know if it’s OK to use. Your list states it’s approved by the VAG brands but I’d personally not use it; I’d wait until I got some G12 Evo.
2020 Polo GTI Plus; Pure White, DSG (because they all are)
Gone but not forgotten;
2016 Polo GTI; Blue Silk
2011 mk6 Golf GTD; Carbon Grey
2007 mk5 Golf GT (2.0 170bhp TDI version); Deep Black Pearl
2002  mk4 Golf GTI (the 150 bhp diesel version); Deep Black Pearl

Offline davo245

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Re: MK8 GTi coolant warning light
« Reply #5 on: 10 August 2026, 07:53 »
Thanks guys I will have to try and grab some from VW dealer in the morning.

I don't suppose I can use this

COMMA®
Xstream
G40
Antifreeze & Coolant

CONCENTRATE
Protection down to -52°C*
Glysantin® G40® by BASF is approved by:
Audi/Bentley/Bugatt/Lamborghini/Seat/Skoda/W/Porsche vehicles (TL774-G),
Liebherr (MIN LH-01-COL3A), Cummins (CES 14603), Deutz (DQC CC-14), MAN Truck & Bus (MAN 324 Typ Si-OAT), Mercedes-Benz Cars (MB-Approval 325.6).
Mercedes-Benz Truck & Bus (MB-Approval 325.5), MTU (MTL 5048),

I don’t know if it’s OK to use. Your list states it’s approved by the VAG brands but I’d personally not use it; I’d wait until I got some G12 Evo.

This ^^ VW coolant only imo
Mk6 GTI DSG
MK7.5 GTI performance DSG
Mk8 GTI