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Model specific boards => Golf mk7 => Topic started by: Deddi on 27 November 2025, 20:49

Title: Coolant silicon bag
Post by: Deddi on 27 November 2025, 20:49
I have had a good read of the posts on this issue and have decided to take the bag out.

I just want to make sure I have this right before I do it please,:

Looks like I have G13 in my car now (2016 GTI) according to what I have read. Also seems that I need a different version of coolant once the bag is removed - is it G12 evo?  So when I have removed the bag, is it ok to put some of the G12 evo in to top up the system, is mixing coolants ok? Then at some point in the future, flush the whole thing and fill with just G12 evo?

Thanks
Title: Re: Coolant silicon bag
Post by: smig on 27 November 2025, 21:36
This suggests its OK to mix https://www.coxmotorparts.co.uk/product/vw-shop/volkswagen-g12-evo-coolant-1l-5l/?srsltid=AfmBOoqH709q94Gn0CZBHTBf7hQKJufoRWC_JPFGuqR_ANurPjJ-6r9z
Title: Re: Coolant silicon bag
Post by: SuperScaff on 28 November 2025, 05:46
That’s exactly what I’ve done and had no issues,
Title: Re: Coolant silicon bag
Post by: Adam T7 on 28 November 2025, 06:02
I could be wrong but I understand that the silica bag was put in place to stop the degradation of the G13 cooling and corrosion resistance over time? I took mine out a few years ago and now just drain the expansion tank and replace with fresh G13 every year and then test with a floating disk tester. The stuff in the link above seems a better choice though.
Title: Re: Coolant silicon bag
Post by: joe6 on 28 November 2025, 08:56
That’s exactly what I’ve done and had no issues,
Did this too. No issues either.
Title: Re: Coolant silicon bag
Post by: MEZZA on 28 November 2025, 22:20
Just looking at other forums about this issue and came across a silicate cartridge you can get instead of a bag - looks like a small white cylindrical plastic object that goes inside the expansion tank and you can get them for about. £20.00 - supposed to be stronger than a bag but still need changing every few years - unclear as to if you just place it inside the tank or maybe there is specific tank for them - as been mentioned, VW put the bags in to help prolong coolant anti corrosion properties and unless you change to G12 Evo keeping to G13 without the bag could compromise this? Google VW silicate cartridge and you will see them - anybody have more info on this  ?
Title: Re: Coolant silicon bag
Post by: Deddi on 28 November 2025, 22:56
Thanks for the replies everyone, very useful 👍
Title: Re: Coolant silicon bag
Post by: Rudedog on 29 November 2025, 10:08
I'm having my matrix replaced next week at my dealers so I'm hoping they will have to drain the whole system which means they'll have to replace with G12 Eco.  As I've mentioned I took my bag out within 6 months of buying my car over 5 years ago.
Title: Re: Coolant silicon bag
Post by: 2007GTI on 03 December 2025, 11:27
As you'll see from my recent thread, I just had matrix replaced in my car and thanks to reading this, I have put in G12 Evo, as silica bag removed too.

VW wanted £42 for 5 litres, so I got this one for half the price, and it is made to VWs spec:

https://www.eurocarparts.com/p/mpm-coolant-premium-longlife-40-c-g12evo-ready-to-use-5l-523772601


Title: Re: Coolant silicon bag
Post by: david25 on 04 December 2025, 15:35
Cartridge for anyone interested

https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/silicate-cartridge-for-expansion-tank/4e0121176/
Title: Re: Coolant silicon bag
Post by: 2007GTI on 04 December 2025, 20:17
What is the idea for adding one of those?

When you go thru options it says it doesn’t fit Golf GTI?

Also surely they can be found in UK? that is in USA, shipping will be expensive.

Cartridge for anyone interested

https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/silicate-cartridge-for-expansion-tank/4e0121176/
Title: Re: Coolant silicon bag
Post by: MinchCS on 04 December 2025, 21:04
To replace the silicate bag with something a) new and b) more robust. It is not designed for our water bottles but, by coincidence, clips in where the bag used to sit. It's an option if you want to remove the bag but want to avoid the inevitable coolant change required if you do as existing coolant will age quicker without the silicates.

See here: https://www.vwroc.com/forums/topic/38040-coolant-bottle/page/3/

PS, when I say new, I am referring to it being in better nick (and therefore less likely to fail) than your 10 year old bag, not that it contains anything new or fancy,
Title: Re: Coolant silicon bag
Post by: Rudedog on 04 December 2025, 21:19
Even G12 Evo? I thought as that is in the newer cars that don't have the bag then it was ok for a lot lot longer.
Title: Re: Coolant silicon bag
Post by: MinchCS on 04 December 2025, 21:43
No. Not needed with G12 Evo. This is for cars with G13 that originally came with the silicate bag.
Title: Re: Coolant silicon bag
Post by: 2007GTI on 04 December 2025, 22:38
Oh right, I’ve gone G12 evo, so no need to.
Proper!