This sounds a simple question but if my frost protection is low when i measure it just how do i know which of the two coolants are in there already ? I understand from reading other posts that there are two basic types of anti freeze (and the colour does not matter), but how do i know which of these is already in my tank so i don't mix them up should i add the '' other '' one ?

 

Also i have recently started to get the red coolant alarm come on during the cold mornings, i understand this is a known fault with these cars, when i switch the engine off and back on again it clears.

 

Ta.

Normally the coolant expansion tank has it stamped on it, ie. G13. And is normally pink, do not mix different colours.

Easy answer is to fix the warning light problem by replacing the header tank, this means you'll have to drain some coolant, once replaced simply top back up with pure concentrated Ethylene Glycol to increase your freeze protection.

 

The only reason mixing Propylene and Ethylene Glycol is bad practice from an engineering standpoint is because they both have different heat transfer and anti-freeze characteristics, this makes it very difficult to determine how the resulting mixture will behave, not because anything bad will happen.

do not mix different colours.

 

Why not?

 

Edit: The colour is just a DYE, G12 is fluorescent pink so that you can use a UV lamp to help with leak detection, in the US they use fluorescent green, same stuff though. Topping up G12 with blue glycol gives a pretty lilac coloured coolant.

Edited 7 February, 201511 yr by sepulchrave

G12 or G13 is ok do not mix green and red !! Im not sure how well G12 and G13 mix together but i think its not so harmful than mix red and green ones....
Where i live i use to made half and half  and  it shud be give about minus 35 or moore....And if you are not sure what you have there all ready then i recomend use G12++...

http://www.skodaparts.com/product/g13-coolant-50247

 

Edited 7 February, 201511 yr by FinnVrs

do not mix green and red !!

 

Yeah, that would make the coolant BROWN and it would look HORRIBLE! Right?

Yep

I thought the reason why you can't mix the OAT (G12-14) with ordinary Glycol (G11) was it not only changed colour, but reacted and gunked up, therefore greatly reducing the cooling ability.

I thought the reason why you can't mix the OAT (G12-14) with ordinary Glycol (G11) was it not only changed colour, but reacted and gunked up, therefore greatly reducing the cooling ability.

 

No, it doesn't do that at all. OAT is just part of the additive pack for corrosion inhibition, it's still Ethylene Glycol.

That must be a scare storey to stop people mixing them

That must be a scare storey to stop people mixing them

 

You're right, it's a myth repeated by non-technical people and therefore the internet.

 

From a pure engineering standpoint mixing isn't desirable because you end up with a solution which has unmeasurable properties and for which you can't exactly determine the levels of protection available.

However from a practical standpoint it is better to have a solution with a higher Glycol content than not because Glycol itself also offers inherent anti corrosion properties. There was a 'trend' for using OAT instead of traditional Silicate anti corrosion additives although it is now generally accepted that there is no real advantage in doing so.

 

The truth is that you can mix whatever you like for the purposes of topping up, the same as you can with engine oil, it's better to add Glycol than tap water and it's better to have the correct oil level than not.

Thanks for that, went for its service yesterday and had it topped up with the proper stuff, my mechanic also had a look at the warning light coming on, said he has fixed it.... not had a cold enough day yet to test it.