Which coolant?

[Willy]

I need to flush/refill mine as the RAC man only had water in his van, which does nasty things when it starts to freeze overnight in a month or so's time. By the looks of things mine had the modern pink stuff in the rad (although it's now turned a rather murky orange so I think a change was overdue), and the internet is full of scaremongerers saying don't mix yo coolants, as bad things will happen.

All they have in the local shop is blue (nearest Halfords is 1,000,000 miles away), is this okay? Or should I go for pink?

Cheers, Will

[Tim Leech]

Colour is not that important, I would use a known brand (I dont go to halfords though as they are very pricey) and mix 50/50 with water.

Sometimes the local big supermarkets/DIY stores sell it at a very good price.

I would back flush the radiator whilst your at it and check the hose clips of course.

[robt]

I've used Comma 'Super Coldmaster' anti-freeze in my cars for a few years which has been fine. If the car is new to you it's difficult to know what the previous owner used, so some mixing of the brands is inevitable as coolant will still be in the system somewhere. This happened when i did a coolant change on my Montego recenty and it's been fine, so far....

[mat_fenwick]

OAT (long life) antifreeze is often but not always pink, so I guess that's what Willy is referring to. They are designed to mix OK but if you mix OAT with the other types, you lose the benefits of longer life.

Some people have reported it 'eating' gaskets on engines not originally designed for it, but not heard/seen that first hand...

[Kitch]

Colour can be important. Some anti-freezes are designed for alloy engines only.

You can use blue (which is generally universal so a jack of all trades, master of none) or a red, which is better as it's really designed for all alloy engines (and being a petrol hero, you don't have a lump of iron sitting over your front wheels!). But yes, use either just don't mix colours as they can have a habit of trying to cancel each other out.

[citronut]

it is said in the garage trade you should NOT mix red with any of the others as it will congeal, which can/will clogg up your cooling system,


red is O.A.T and blue, green and i think yellow are
glycol/methanol,

so completly diferent formular's,

if you are flushing the system fully you should be ok putting blue back in as this is what it would have had from the factory,


regards malcolm

[mat_fenwick]

it is said in the garage trade you should NOT mix red with any of the others as it will congeal

I've read that too, but I'm not aware of the antifreeze manufacturers stating that you can't mix them. Most recommend against it as you lose the benefits of the OAT stuff, but still say it can be mixed. I'm willing to be proved wrong though, if someone knows of a manufacturer's warning that they must not be mixed.

Has anyone seen the gelling/congealing first hand? I've mixed the two before with no problems, but that does not obviously mean that it is safe to mix all kinds in all engines.

[Tim Leech]

Surely if you are draining the system then you have no need worry about mixing old and new anyway. When I do mine I always drain the complete system and start a fresh.

[kiwi]

Speaking from recent personal experiances on changing coolant in two of the BXs. What I found with flushing and then filling with fresh antifreeze was leaks appearing. No idea why but this scare story of differant types not mixing "my" or "may not" have some merit.

On the subject of colour the most common colour here is Green yea spot the leak

[Discoil]

reminder to ones self

Check antifreeze strength as it's the green stuff ( unipart ) and its been in about 10 years now. OOOOOooooopps

[mnde]

it is said in the garage trade you should NOT mix red with any of the others as it will congeal

I've read that too, but I'm not aware of the antifreeze manufacturers stating that you can't mix them. Most recommend against it as you lose the benefits of the OAT stuff, but still say it can be mixed. I'm willing to be proved wrong though, if someone knows of a manufacturer's warning that they must not be mixed.

Has anyone seen the gelling/congealing first hand? I've mixed the two before with no problems, but that does not obviously mean that it is safe to mix all kinds in all engines.

What Malcolm wrote is also the advice I'd heard. TBH Mat I wasn't about to find out about the gelling/congealing if I could help it. I thoroughly flushed my BX's cooling system as best I could when I was changing the old blue coolant - draining, and refilling with water mixed with a flushing agent, running the engine according to the flushing agent instructions - heater tap fully open etc - , draining again, followed by running the engine with the cooling system filled with plain water, draining, and flushing the rad with a hose - before refilling with a 50:50 mix of red/orange OAT coolant. I used OAT because as Kitch says it's designed for alloy engines.

So yes, colour does matter, and also AFAIK if you just drain the cooling system, you won't get all of the old fluid out. There will be some sitting e.g. in the heater matrix.

Mark

[electrokid]

Different colours / types of antifreeze shouldn't be mixed - not ever. Always follow the manufacturers recomendation for the vehicle / engine and stick to that type only.

OAT stands for Organic Acid Technology and should only be used where recommended - normally an ethylene glycol based antifreeze (blue) should be used in the BX and this contains corrosion inhibitors which try to keep the coolant alkaline (and are just as good as OAT in keeping corrosion at bay).

If you remember your high school chemistry...

acids + alkalines = salts + water

If you mix OAT with Bluecol the chemicals designed to prevent corrosion will react with each other (and destroy themselves in the process) and leave solid deposits in the cooling system.