Can you mix different colored cooling liquids? I needed to top up the coolant overflow bottle on my motorcycle as it had dropped below the 'low' level. I went to a car shop shop and bought some liquid-coolant. I mixed it 50:50 with deionized water and topped the motorcycle up and felt very pleased with myself.

The liquid-coolant I bought was a sort of luminous orange and I didn't give it much more thought even though the existing stuff in the cooling system is blue. I've now been told I shouldn't have mixed them and because I have I should change the whole lot now. Is that right?

Quote by: romble

Can you mix different colored cooling liquids? I needed to top up the coolant overflow bottle on my motorcycle as it had dropped below the 'low' level. I went to a car shop shop and bought some liquid-coolant. I mixed it 50:50 with deionized water and topped the motorcycle up and felt very pleased with myself.

The liquid-coolant I bought was a sort of luminous orange and I didn't give it much more thought even though the existing stuff in the cooling system is blue. I've now been told I shouldn't have mixed them and because I have I should change the whole lot now. Is that right?

The rules on mixing chemicals is very basic, never and we seriously mean never mix chemicals if you not know what you're doing.

Second, yes, you need to replace all your cooling liquid and replace it with the coolant liquid recommended by the manufacturer of your motorcycle. Most modern liquid-cooled motorcycles in Thailand don't use water mixed / based cooling liquids.

After you drain all the current cooling-liquid out of your system, you need to check if all plastic and rubber parts are still in good condition. The orange colored cooling-liquid you describe is likely based on organic acids – which can be harmful for some rubber or plastic parts if your system was not build to use that liquid.

Never mix coolant, even different types made by the same company. Also beware of cheap coolants, some actually corrode aluminium. Buy a good brand, or even go for the ones sold by dealers like Honda that their service department use. It might be a bit more expensive but better than getting a new engine!

Sadly you should not mix Orange and Green.

If it was recently and you have not used the bike much, and as all you did was top up the overflow tank, you should be OK to siphon out the overflow tank and replace it with some green "anti freeze". The orange you put in the overflow will not have had a change yet to mix with the coolant in the engine.

If you want to and feel capable of draining the system and starting again OK.