Got my skoda back from the dealer and while in it was given a visual healthcheck... It all fine but the coolant has an advisory and -25 scrawled next to it.... Is that bad and if so is it quite simple to rectify? Cheers!

The -25 refers to -25 Degrees Celcius, the temperature at which it will start to freeze. It could well do with topping up with neat G12.

Ahh ok cool, and I'm guessing I don't need the garage for that? Do I need to drain what's in there before adding more? Really appreciate the help!

Ahh ok cool, and I'm guessing I don't need the garage for that? Do I need to drain what's in there before adding more? Really appreciate the help!

Drain the coolant out of the expansion tank (engine cold) and fill tank with neat G12+ Run engine to mix fresh anti-freeze with coolant. Would be worth having concentration checked after you do this, as the mixture should never be more than 50/50.

Just as a note, you should be able to get a concentration checking tool (looks like a cross between a turkey baster and a thermometer) from somewhere like Screwfix, Machine Mart, etc for not very much, which will tell you the level of anti-freeze protection it should give you.

Would be worth having concentration checked after you do this, as the mixture should never be more than 50/50.

Just out of curiosity (I know this is probably a silly question), but what bad thing would happen if it were > 50% coolant?

Edited 1 July, 201016 yr by martinch

Just as a note, you should be able to get a concentration checking tool (looks like a cross between a turkey baster and a thermometer) from somewhere like Screwfix, Machine Mart, etc for not very much, which will tell you the level of anti-freeze protection it should give you.

Just out of curiosity (I know this is probably a silly question), but what bad thing would happen if it were > 50% coolant?

My understanding is that the recommended mixture for UK use is 50% for protection down to -36 deg C . If a 40% mix is used, protection is down to -24 deg C . A 60% mix gives protection down to -52 deg C These figures are for G12 ++ which is the later coolant spec. So I don't think anything bad will happen if you put too much G12 coolant in but it would be wise to limit it to 60% even if only to protect your wallet contents ! These modern coolant anti-freezes don't just provide lower freezing protection but also provide anti corrosion properties.

These figures are for G12 ++ which is the later coolant spec. So I don't think anything bad will happen if you put too much G12 coolant in but it would be wise to limit it to 60% even if only to protect your wallet contents !

Hehe ... fair enough. I didn't know if they heated up too much, or something like that Mine's running about 50% G12++, purely cos it's easy to measure..!

I know of a case where someone put 100% coolant into a car and it knackered the cylinder head because it ate the metal away. This is the older blue coolant rather than the newer red/pink/purple organic acid based one though.

Oh dear!