Mixing antifreeze - should I be concerned?

[tazzle]

Topping up the fresh-water header tank, I use a 50/50 mix of bog-standard auto antifreeze without much concern.

I've just read an online 'flier' from a supplier with a deal on antifreeze that says "Use a good flushing agent as old antifreeze and new can sometimes react to form a jelly-like substance that will block the pipework."

Aaaargh! There's something else I didn't know. Should I be worried?

 

[macd]

Most green antifreezes (ethylene- and propylene- glycol) are compatible and can be mixed. Your 'bog-standard' stuff will probably be one of these. However, some Organic Acid Technology (OAT) antifreezes are also green (or pink, orange, red or blue...!) and are not compatible. So it depends what's in the engine already and what the stuff on offer is.

See http://www.filtercouncil.org/techdata/tsbs/05-2.html for more info.

 

[FullCircle]

Radders,
I have had the issue with non compatible anti freezes. My Yanmar insists I have the Orange Havoline product. The net result for me was that the heat exchanger fins became clogged, but I think largely due to poor heat exchanger design.
it was changed from 63 fins per inch to 38, so there must have been an issue.
Jeanneau managed this trick from new, as they used whatever they had in the drum at the factory!!

Yanmar came along and changed both the heat exchange and the antifreeze.

If you do need the Havoline Orange (cant remember the product code), nip along to any Vauxhall/Saab dealer and buy the standard General Mootrs Orange, it is the same. Surprisingly not expensive either.

 

[leadersail]

You should use a low or nil silicate formula ethylene glycol.

It is the silicate that separates and forms a silicate gelatin that blocks the heat exchanger.

Tap water should not really be added , de ionised water should really be used.

 

[Avocet]

This is interesting - and completely new to me! I've never come across this problem in a car cooling system! Although I can't be absolutely sure, I'm pretty certain I've mixed all sorts of antifreeze in my cars' cooling systems in the past. OK, they have always been glycol-based antifreezes, but beyond that, I'd never have given it a second thought!