Facts on Coolant Compatibility

Facts on Coolant Compatibility

1.  All coolants are compatible

2.  All the same colour coolants are compatible

3.  Brand X coolant is compatible with everyone's

4.  Its ok to top up a radiator with any coolant

5.  Ethylene Glycol is not needed in a coolant as it's only for anti-freeze

6.  Glycols are corrosive

7.  Disposal of glycol based coolants will be banned

1. Are all coolants compatible? No,

Coolants should not be mixed under any circumstances as catastrophic problems can occur. Nearly all manufactures of quality products will place a statement on their label warning not to mix their brand with other brands. The short term reaction from a cocktail of different coolants is usually a chemical fouling of the radiator and a vehicle that will start to run hot and eventually boil, plus substantial corrosion in severe cases. 

2. Is the colour an indication of compatibility? No

Colour has no bearing on either the quality or compatibility of coolant whatsoever. If colour was all there was to a product you could be fooled into thinking that water dyed green was coolant.

3. Is there one brand compatible with everything? No

All coolants differ by varying degrees. Any salesperson who assured you that their product is compatible with all or most other coolants is either ignorant or trying to mislead you.  If you are told this story by a supplier ask them to confirm it in writing, remember it's you who will be picking up the tab for their mistake.

4. Can I top up a radiator with any coolant? No,

The same rule applies as to question one. No amount, no matter how small, should be mixed. It is safer to use water for top up in an emergency and then replace the coolant with the original brand within a short time.

5. Glycol only acts as an anti-freeze? No

Glycol serves several purposes in today's modern coolant. It allows the use of better quality inhibitors, converts film boiling to nucleate boiling in the hot spots that exist in the vehicle's aluminum head, around the exhaust valves and provides lubrication to moving valves, relief valves in the pressure cap, thermostat slides and water pump seal faces.

6. Is glycol corrosive? No

Due to the total package of inhibitors and buffers in modern coolants, glycol has no adverse affects on corrosion. 
The vehicle industry as a whole, world wide, recommend the use of glycol based coolants and inhibitors. 
Can the automotive industry world wide be wrong and some obscure manufacturer who wants to make cheap glycol free coolant be right? 
7. Are glycol based coolants environmentally unsafe? No

Glycol is total biodegradable. The problem with coolant is that it picks up heavy metals as it circulates in a vehicle's cooling system. 
This applies to any fluid, water, non glycol coolant and glycol coolant, so disposal of any used coolants should be done in accordance with local regulations. Remember this situation applies to all fluids, so if you're told that it only applies to glycol based 
coolants you are being misinformed.