Is mixing different coolants REALLY bad?

[OldSkodaDriver]

I just topped up my Skoda with coolant: BLUECOL'u' clear.
It said:
'Universal top-up antifreeze & coolant'
'All makes - All Models'
'Will mx safely with all colours of antifreeze'

Then I dug out the manual which states:
'The same coolant (G12) (red in colour) MUST always be used for topping up.'
'Mixing different coolants can result in damage to the engine'
'Have the coolant replaced immediately'

Is this true?
Thanks.

2002
Skoda
Fabia
1.4
40,000 miles

[S0 What]

Some engines need the the anti corrosion propertys in certain AF, mixing oat and glycol is not good, they end up as a semi solid jelly like substance that blocks waterways, as a rule of thumb just stick to what the manual says.
Oh yes and read the handbook before not after.

[VAGslag]

Worse than jelly like substances, mixing coolants can cause a thick crusted on crystallization which not only blocks coolant flow but also seriously hampers heat transfer

We had an R32 golf in once. We took the head off I couldn't believe the amount of crystallization!

[Petrolhead_Rich]

anti-corrosion for different metal types in different coolants, plus as above mixing can result in jelly/crystals forming.

Even through the stuff you're describing sounds like some sort of snake oil magical we do it all stuff, I'd Drain it out asap and fill it with the correct stuff!

Also if it needs topping up, sort out why it's loosing it!!

[OldSkodaDriver]

Thanks for all your replies:

Here is the reply I got (very quickly) from the manufacturer:

'Bluecol ‘U’ has been tested with coolants such the G12 type and is fully compatible to use with this product therefore you should have no worries regarding the formation of any deposits that would cause problems in the cooling system.


Regards,


Shazad Shah



ETA

Sorry but signatures are not allowed.

Edited by Big Al. on Monday 10th October 19:16