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changing antifreeze this weekend. Currently blue stuff in it (B202, 2l 16V engine). other posts recommend red. On Comma's web site, their blue stuff meets saab requirements but does not say if it's safe for alloy block. Red stuff is. which do I go for?
 

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Welcome to Saabscene.

I'm don't know anything about Comma antifreeze, but if you are planning on keeping the car, you may wish to use one of the longlife products (as Saab currently use) so that you don't need to change the fluid in 3 years time. The block's iron by the way, it's the head that's alloy.
 

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Welcome onboard Brock.

I checked the Comma spec and used 'blue' (3 year lifespan) on my Nov service, because it was approved by Saab (as stated on the container label). This will definately cover alloy heads and blocks.

The 'red' option (5 year lifespan) does not state Saab approval, and 3 years with Saab approval was my preference.

I note the blue container stated, "Do not mix with any other anti-freeze". Presumably the red does as well.

Which raises another issue.. How to get all the old fluid out!

I found that after draining the coolant, I could only get 7 litres back into the system (to the max mark of expansion tank) although handbook (for my '98 Anni 2.0L) states system holds 9 litres of coolant!

I disconnected lower hose at base of water pump, as this was the lowest and most accessible jubilee clip on my car. I had previously warmed the negine and set ACC to hot, to ensure valve was open.

NB: Do NOT use the plastic drain plug on bottom of radiator - as it usually snaps off - and being hollow, won't retain water - so your car will be out of action until replacement sourced!


So I can only assume there is up to 2 litres of old (50/50) coolant still in the system, and that bottom of cooling system (i.e. in block) is lower than the bottom hose, or the heater matrix sits lower than the supply/return feed pipes!

In any case, flush the system - and run engine between replacing coolant - to flush as much old coolant out of this 'pocket' as possible - and be sure to add all of the 4.5 litres of fresh antifreeze before you have filled up with 7 litres it will take - or the final ratio will be less than the prerequisit 50% antifreeze.
NB: Best if you add new coolant ready mixed at 50% ratio - assuming you have a suitable container to do so.

HTH,

Paul.
 

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Just done a coolant replacement on mine and had decided to use the 5-year red Comma stuff but then couldn't be fished to remove the thermostat to flush out all the old blue stuff.

The instructions on the back of the Comma pack are a bit contradictory in that they do say that it's compatible with 'traditional silicate antifreeze' but then go on to 'recommend' that any blue/green/yellow antifreeze be thoroughly flushed away before filling with red. So I phoned them.

The answer, apparently, is that, while the red is indeed fully compatible with blue etc, any dilution of the red by residual blue etc stuff reduces the protection span pro-rata from 5 years to somewhere in between 3 and 5 years, depending on how much of the old stuff is left in. I refilled with blue.
 

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 I had previously warmed the negine and set ACC to hot, to ensure valve was open.[/b]
You needn't have bothered, there is no valve. The ACC, and the manually operated heating system, contols the temperature by a flap mixing hot air from the matrix with cold air to achieve the desired temperature. Sorry if I'm being pedantic about this.
 

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Which raises another issue.. How to get all the old fluid out![/b]
Empty the coolant via the bottom rad drain plug, fill with plain water and then flush through plain water with the engine running. Keep topping up with plain water until you've passed through a good couple of dozen litres then begin introducing the antifreeze or coolant mix. I did it by leaving some water in the system and then introducing the neat anti-freeze into the system and getting the water pump to mix it, which is a bit lazy and probably not the most gentle method.

The better method would be to flush through some of the new coolant until the coolant being lost from the radiator drain hole is the same colour as the coolant you're filling it with.
 

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Derek,

Thanks for the info. Whilst I wasn't sure - so took a couple of seconds to press a couple of ACC buttons, I/we now know for next time!

Jason,
You seem to have missed my warning not to use the radiator drain plug - as the plug head often snaps off on older cars due to plastic ageing through time/heating effect. Definately use the lower hose conection as it's much more robust, and actually fractionally lower than the drain point.

Your comments on 'flushing' concur with my conclusion above.

Would be interested to know where the extra 2 litres are retained, during the draining process. Is it the heater matrix? - in which case I assume it must be located below the feed pipes.

B-regards,
Paul
 

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Jason,
You seem to have missed my warning not to use the radiator drain plug - as the plug head often snaps off on older cars due to plastic ageing through time/heating effect. Definately use the lower hose conection as it's much more robust, and actually fractionally lower than the drain point.[/b]
Yes, you are quite right. I was speaking from the point of view of someone with a rad that was only a few months old. For those who still have their original rads using the bottom hose is the better idea.
 
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