Antifreeze ( coolant)

[froggy]

Hi, just about to change the coolant in the cars. which is the preferred choice , red or blue coolant, many thanks in advance Terry.

[superloopy]

My 95 TD is blue if its any help.

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[CitroJim]

Blue (ethylene glycol) always in an older engine that currently has blue. To change to a red OAT based one needs a full flush first as the two don't mix... Mixing the two can have quite dire consequences...

[froggy]

Hi Jim, probably a silly question but what would happen if you mixed the two ? Terry.

[Hell Razor5543]

Probably an acidic syrup!

[RichardW]

Allegedly the two can create a gel, which would cause a few problems in the system...

Note both are ethylene glycol for antifreeze effect - the difference is in the corrosion inhibitors.

[Zelandeth]

Apparently when the two mix the corrosion inhibitors react with each other which produces a hard crystalline sediment which enjoys doing things like wrecking water pump bearings and blocking thermostats.

Xantias originally had the old green/blue type coolant I believe.

Either are safe to use though, just bear in mind that if you're changing you'll want to do a good thorough flush first.

My 1989 Saab 900 has been running red OAT coolant for five year or so now (it's what I had on hand when I changed it) and there have been no problems whatsoever as a result - just flush first and you should be fine.

[froggy]

cheers

[BX]

There is also a yellow antifreeze which is compatible with both of the other types. It is very useful for when you do not know what is in there already and you need to top up. Its life span depends on what other type it is mixed with.

[xantiagreen]

Hi Jim, probably a silly question but what would happen if you mixed the two ? Terry.

Oh no that's dangerous that is, you'd end up with a mutation something along the lines of flubber, I think Citrojim has some forming in the bottom of his batch of LHM...

[Jaf]

Can I still use Forte stop leak with red antifreeze? I just bought some...so glad I read this thread!

[CitroJim]

Yes, it's (as far as I know) compatible with all types of coolant.