Here are some points about coolants I've gathered from around the internet. Please feel free to correct any misunderstandings so we can all learn and get away from the vehicle industry using fear and uncertainty to sell its own products which are often unavailable locally.
I have been in contact with Yamaha who have been evasive about what type of coolant Yamacool actually is. This means you can try to follow their Service Manual guideline ("High-quality ethylene glycol based antifreeze containing corrosion inhibitors for aluminum engines") but don't really have enough information so have to make some assumptions and determine the gold standard yourself.
1. Colour of coolant doesn't mean anything anymore, its just a dye added to the clear coolant liquid. For example Valvoline Zerex Asian Blue coolant is the same as Valvoline Zerex Asian Red coolant. If you have red coolant from the factory in your radiator, Valvoline don't want you to avoid their product because the colour is deferent so they provide the same coolant in 2 different colours.
2. IAT (Inorganic Acid Technology) coolant was used in old vehicles from decades ago. These days all vehicles have a version of OAT (Organic Acid Technology).
3. Never mix IAT and OAT coolant as it will likely react and form a gel in the system. However, IAT is unlikely to be in your system if you have a vehicle manufactured in the last 25 years!
4. It is best practice to flush out the cooling system with
distilled water between coolant changes, especially if the coolant hasn't been changed in the last 5 years, and use a coolant flush additive if you are in any doubt (old vehicle/unsure about existing coolant type)
5. Silicates or phosphates are the most common corrosion protection additives used with OAT based coolant types. They are both synthetic additives giving rise to the Hybrid part of HOAT (Hybrid Organic Acid Technology) coolant type designation. A coolant using silicates or phosphates as a corrosion inhibitor can also be known as "Si-HOAT" and "P-HOAT" respectively.
6. Silicates can fall out of suspension from HOAT coolant and form a kind of white flake/powder in the coolant when it is cold. This dissolves back into the coolant as it warms up so should be nothing to worry about.
7. Silicates form a protective layer in the coolant system to prevent the water in the coolant from corroding the cooling system, but silicates can be unkind to seals, gaskets and hoses over a long period.
8. Instead of silicates, phosphates may be used to prevent corrosion in the coolant system. Phosphates are used mainly in Japanese/Asian cars because the tap water in Asia is not "Hard" water, which is water containing high levels of minerals (calcium and magnesium). The problem with phosphates and hard water is that the phosphates can react with the minerals to form a sludge which restricts flow in the cooling system. Presumably as many parts of Europe have hard tap water, P-HOAT coolant is not commonly available in Europe.
So what does Yamaha's specification ("High-quality ethylene glycol based antifreeze containing corrosion inhibitors for aluminum engines") imply? For me it implies the use of OAT coolant with either silicate, phosphate (or other) corrosion inhibitors HOAT, Si-HOAT or P-HOAT.
Elsewhere in the Yamaha Service Manual it suggests when mixing-up fresh antifreeze concentrate and water to make a coolant, to use only
distilled water, or if that is not available to use "Soft" water ("Use only distilled water. However, if distilled water is not available, soft water may be used"). Soft water is water that has been treated, removing any calcium and magnesium. Yamaha could be implying that they use P-HOAT coolant from the factory and that Yamacool is in fact a P-HOAT coolant. However if P-HOAT was used, I would expect Yamaha to be more explicit that adding hard water could result in poor coolant flow and over-heating.
As for me, I would use Zerex Asian
Blue P-HOAT coolant, but as I live in Europe it's hard to find and expensive. Instead I intend to flush my bike's coolant system thoroughly and use Motorex M3.0 which is silicate and phosphate free and widely available so not too expensive. I think it should be classed as a HOAT coolant as its OAT with anti-corrosion additives making it a Hybrid OAT coolant, but Motorex only write "OAT" on their packaging. From then on I will stick to the same coolant for all subsequent coolant changes.
The only issue with M3.0 coolant is that it's pink which is VERY hard to see through the side of a motorcycle's white plastic reservoir tank. I can see this putting a lot of motorcyclists off, come on Motorex, offer M3.0 in a darker colour!
Note: Motorex M5.0 is silicate based and used to be recommended (by KTM) for KTM motorbikes. However, several years ago KTM switched to M3.0, even for those bikes (that Im aware of) which used to be recommended to use M5.0... so don't go thinking M5.0 must be an advance on M3.0!
Thanks to this great online resource and many other online contributors:
Here at Valvoline, we have already discussed engine coolants in depth. We wrote about the importance and application of these specialty fluids. If you are still not sure which types of coolants there are and how to pick the right one, do not fret. Valvoline has got your back. We compiled the...
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