Switching to Suzuki Super Long Life (blue) coolant

TL;DR Some say the orange coolants eat the radiator when left sitting for too long

In the end, it was replaced on March 7th.  Jump to this post to read it.

I couldn't clearly remember what brought me to the coolant rabbit hole. 

Trying to find the source material back, I think it was probably when reading the Caterham 7 diaries blog that the recurrent radiator failures came to my attention. What I know for a fact is that I did discover the blog with the post about upgrading the handbrake sleeve.

Anyway, the issue seems to be that standard pink-orange coolants do not like to be left sitting in a sleeping car for extended periods of time. This is how Radtec understand it, and why they advise the use of "blue" coolant.

So here we go with the rabbit hole, and what I got from the various readings on the topic :

• Coolants are basically a 50/50 mix of antifreeze (ethylene glycol+additives) and distilled water
• The antifreeze prevents freezing down to ca -40°C, and does also increase the boiling point of the coolant over 120°C
• Having more antifreeze than recommended (>50%) is counter productive as water is better at transporting heat.
• Glycol is tasty to pets and wildlife but is very toxic (kidney failure).
• There are non-toxic water-less coolants with a very long lifetime, but they are not as good as moving heat away.

• Additives are mostly there to protect the cooling system from corrosion
• Old cars used to have IAT (inorganic) additives with phosphate-silicate, they are usually colored in yellow-green. They needed to be changed every few years.
• Recent cars use OAT (organic) additives with no silicates, and they can last longer. They are usually colored in pink-orange and are the most current type used in Europe.
• Fancy HOAT (hybrid OAT) add either silicates (in Europe) or phosphates (in Asia). It seems that water mineral content (hardness) plays some role in those choices.
• PHOAT seem to be what Radtec are referring to when talking about blue coolant. 
• The local Suzuki dealer confirmed that they are using blue coolant, an OEM product supplied by Suzuki themselves.

Here is a good resource page from Valvoline if you want to know a ton more.

And here is is what Suzuki say on their product page : "Suzuki performance long life premix coolant is specially blended from a formula containing corrosion inhibitors, providing outstanding aluminum protection and designed for a longer service life. Blended to protect and lubricate water pump and seals. while resisting high rpm foaming."      I have a Suzuki engine and want to extend the radiator lifetime, what's not to like ?

I thought that the Caterham service schedule was asking for replacement of the coolant after 2 years, but it's actually a 4 years/40 000km item.

Anyway, this seems like a good winter project. Let's do it earlier than required.

To switch from one coolant to another does require a proper flushing of the circuit. From what I've read, here is what it would look like :

• with the heater valve fully open...
• drain the pink coolant from the radiator bottom plug (it has be to collected and properly recycled)
• flush 3 times with distilled water
• fill the engine with 5 liters distilled water
• start the engine and let it reach operating temperature
• let it cool, then drain again
• finally fill in with 5 liters of blue coolant, make it run a bit, then fill to the "Max" line of the expansion bottle.

The Suzuki Long Life coolant is reasonably priced (~7€/liter) and distilled water from the grocery store is cheap. As the garage gets the coolant in bulk, I will have to bring empty containers, I'll take 7 liters so I have some to top-up between replacements.

Update on Jan 20th 2025 : I already got 15 liters of distilled water in 5 liter containers, and the latest empty screenwash 5 L containers should be appropriate to get the coolant from the Suzuki dealership. I just have to wait to get the car back from the engine upgrade.

 

To be continued - hopefully completed before I print the blog to a book.

In the end, it was replaced on March 7th.  Jump to this post to read it.