Mixing coolants

Submitted: Thursday, Jun 19, 2003 at 21:12
ThreadID: 5548 Views:8056 Replies:5 FollowUps:2
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Gday all, how much damage could mixing different coolants together do? The reason i ask is the radiator was flushed recently but wasn't filled with anti-freeze. As i'll be spending the winter in Jindabyne is it all right to drain a few litres out of the radiator and tip in the right amount of antifreeze/water till its full and pressurised again. The container says not to mix different brands, but its all the same stuff isnt it? Thanks Andrew
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Reply By: Truckster (Vic) - Thursday, Jun 19, 2003 at 21:19

Thursday, Jun 19, 2003 at 21:19
For what its worth to drain a little out, why not drain it all out and put in the good gear????

Do it right do it once.
AnswerID: 23027

Reply By: Martyn (WA) - Thursday, Jun 19, 2003 at 21:27

Thursday, Jun 19, 2003 at 21:27
If you do a search on coolant I had a long thread all about the pros and cons of mixing coolants, concentrations etc etc etc. If you can't find the info let me know I've become a bit of an expert through the forum.Keep the shiny side up
AnswerID: 23028

Reply By: awill4x4 - Thursday, Jun 19, 2003 at 23:04

Thursday, Jun 19, 2003 at 23:04
Andrew, check out www.are.com.au and have a look at the horror pics in the technical section. I think you'll change your mind about mixing coolants after seeing some of those pics.
Regards: another Andrew.
AnswerID: 23041

Reply By: Allyn (Pilbara) - Thursday, Jun 19, 2003 at 23:13

Thursday, Jun 19, 2003 at 23:13
from what I've heard some coolants are not compatible and actually set. I also heat that most of this has been eliminated but you can never be really sure.
Drain it all and start again is my advice
AnswerID: 23043

Follow Up By: GaryInOz (Vic) - Friday, Jun 20, 2003 at 00:11

Friday, Jun 20, 2003 at 00:11
coolant cheap, engines not!
FollowupID: 15266

Reply By: Derek - Friday, Jun 20, 2003 at 21:42

Friday, Jun 20, 2003 at 21:42
Andrew. You simply cannot mix coolants! It's Russian roulette as to whether they will react with each other and coagulate. Drain your present coolant and ideally run a reputable flushing agent through the system. Then fill with clean water and drive around for a few hours with the heater valve open. Drain and refill and repeat until the water stays clean. Then drop the water and fill with your chosen coolant/anti-freeze. As someone above said 'coolant cheap, engines aren't!.. Happy motoring.
AnswerID: 23105

Follow Up By: Peter L - Saturday, Jun 21, 2003 at 16:02

Saturday, Jun 21, 2003 at 16:02
Andrew, the above is good advice but check assorted web sites for info and read thoroughly.

For what it's worth my summary is as follows:

1/ Heater must be on "Hot" to ensure circulation within the entire system.

2/ Because of the design of most systems it is not possible to easily drain ALL of the contents, so drain what you can(80%), then (when the engine is cool) fill up with "suitable" water.

3/ After bringing the engine to operating temperature (so that the water circulates through the entire system and dilutes any remaining coolant) drain again.

4/ If the coolant was of good appearance you can now refill with the correct amount & concentration of the appropriate coolant.(aluminium compatible?) If coolant was looking rusty or contained "gung" then a flushing agent should be used.(An alternative to commercial flushing agents is to use 100% white vinegar(available from supermarkets for about $0.70/litre) It is suggested that this is less harmfull to seals etc than the flushing products.

5/ When filling the system allow for the fact that adding the final amounts will be VERY slow due to the need for air to escape via the closed thermostat.

6/ 100% Glycerol will be marked as "Active Constituent 1080 grams/litre"
Most vehicles will require 33% or 50% concentration (check your owners manual)
Dilute only with "suitable" water (generally de-ionised/distilled)
Be VERY carful when purchasing the coolant as there are many products available as coolant with as little as 30 grams/litre.

FollowupID: 15339

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