G12 Coolants

[hiltow]

Has anyone who has moved over to using Volkswagen G12, G12+ or G12++ coolant in their car ever developed problems with coolant leaks?

Can anyone confirm that any of these coolants are safe for use in the Scirocco Mk1/2 engines? e.g doesn't attack rubber seals etc.

[Nate]

should be G11 blue in these iirc, which is not compatible with red, pink, green or purple

[hiltow]

You're right, G11 is specified for the car.

Some of you might have read my post a few months ago about the car wanting to run hotter. To cut a long story short, the G11 stuff was flushed out and replaced with an OAT antifreeze by the garage. After a few miles the temperature of the car was much more like normal, so problem fixed.

OATs is much thinner, and therefore better at flowing around the engine, esp the head. However, I'm now getting weeps of coolant from the bottom hose and the expansion hose, so I'm going to drain and flush the system.

The only G11 spec antifreeze widely available is the Comma Extreme G48 stuff, which is what I'm more likely to change back to.

The G12++ is a hybrid OAT that can be mixed with G11 and G12, so I'm wondering if this could be an option. That said, it's still an OAT antifreeze, and could end up finding its way out of hose connections like this stuff has, hence me asking if anyone else has had any problems with it.

[go-for-it1]

OAT????

[hiltow]

OAT????

OAT = Organic Acid Technology - this is the latest spec for antifreezes. The G12 series are OATs.

[MacColl]

I'm sure I had read on somewhere like CGTI or Club Polo a while back that G12+ was fine to replace the original G11 blue coolant.

So I have the G12+ in my 89 GT just now. It does worry me however that I do have a leak in the manifold to head where the O ring is for the water way and there has been a leak at the water flange at the end of the head. I do however know that these respective O rings can become perished and leak eventually anyway.

You've got me thinking now when I fit the new O rings do I revert back to G11? Temp wise car is spot on as it is with G12+

[ianaudia4]

I'm sure I had read on somewhere like CGTI or Club Polo a while back that G12+ was fine to replace the original G11 blue coolant.

So I have the G12+ in my 89 GT just now. It does worry me however that I do have a leak in the manifold to head where the O ring is for the water way and there has been a leak at the water flange at the end of the head. I do however know that these respective O rings can become perished and leak eventually anyway.

You've got me thinking now when I fit the new O rings do I revert back to G11? Temp wise car is spot on as it is with G12+

Water flange on the side of the head are only about a fiver from the dealer, they leak eventually because they warp with age.

[MacColl]

Cheers Ian

I've got a new spare plastic one with O ring to go on when I get a chance.

[hiltow]

So I have the G12+ in my 89 GT just now. It does worry me however that I do have a leak in the manifold to head

It's things like this that are giving me the jitters about using anything other than G11 now, even though the car runs better on the OATs stuff.

I spoke to my local VW parts specialist who sat that G12++ will be fine, but you know when you're just not quite totally convinced. That's why I though I'd throw the question open to the forum as I know in the past I've read posts on here from people who say they're using G12.

I'm just concerned that, whilst a weep from a hose is easy to deal with, the consequences of dealing with a manifold leak or leak from the heater matrix connections doesn't bear thinking about.

[Tim_R]

The way I see it if your pipes, seals, gaskets and clips are not doing their job properly then it won't matter what type of coolant you put in, it will find it's way out under pressure when the system is hot.

I'm running G12+ in my 9a engine and haven't had any issues that I would say are due to the type of antifreeze I'm using, yes I've had small leaks but it's been due to a hose that has perished, a flange warping on the head and pitting behind a seal seat due to corrosion. All have been issues due to age.

My system did get thoroughly flushed through with a hose inserted in the header tank before i filled up with the G12+ when i did swap it.

[scala92]

G12+ is the worst of all in 8v engines with rusty deposits/sludge forming depsite flushing and lack of cooling due to a film it deposits on the internal metal surfaces.

Best using G11, Comma Extreme G48 which is the same as BASF made for VW under the spec G11. Side by side there is no differnce. Comma Extreme G48 is at Halfords as £23ish iirc.

G12++ is Comma Extreme G40 at Halfords. Much better G12 stuff but not really meant for older engines and BASF state that.

[hiltow]

The way I see it if your pipes, seals, gaskets and clips are not doing their job properly then it won't matter what type of coolant you put in, it will find it's way out under pressure when the system is hot.

True, but all hoses and connections are good. It's more than a coincidence that it should begin leaking from two locations at the same time when there's been no problems before.

All the comments have helped me decide that I'm going back to the G11 (Comma Extreme G48) and sticking with it. It's just a matter of waiting for a decent weekend day weatherwise to hit the job of getting the system throroughly flushed out to avoid any reaction taking place when the G11 goes back in. This was done before the change to the stuff in now and there has been no problems in terms of reaction / sludging.

[MacColl]

This thread has put my mind at rest somewhat..
http://www.clubgti.com/forum/showthread ... 11+coolant

[hiltow]

Flushed the system today and returned back to using G11.

Filled up the system and went for a test drive. Temperature gauge shot up to 3/4 without the cooling fan kicking in. Got home and found the bottom hose was still cold. gave the car a quick rev and seconds later the temp came down a bit and the bottom hose was warm.

Took it out for another test drive and the same happened - got cak and the bottom hose was cold again!

Weird. I think I might have an airlock, despite bleeding the system. Next time it's fine at weekend I'm going to drain the system, check the thermostat and refill it again.

At least today hasn't been in vain - I've got peace of mind that the purple OATs stuff is ow out and not able to begin trying to create leaks again.

[Nate]

that would suggest airlock or sticking 'stat. did you make sure heater was set to hot when you filled it?