Prius C Two Part Cooling System

[Mr_Luke]

I had my radiator flushed and new compatible coolant added about 3 weeks ago. Since then I've learned more about the car and saw a youtube video of a guy who drains and refills his Prius C and I was thinking about doing this myself. The inverter has a coolant system of its own that seems to stay separate from the radiator coolant, altho they share the radiator.

The inverter coolant is red and it tested to be effective in extreme temperatures. Does this mean it's good coolant and I don't need to replace it yet?

They say the inverter coolant doesn't need to be changed as often because it's a smaller system of 1.7 quarts vs about 5.6 quarts for the radiator / gas engine system.
I'm wondering if I should drain them both and refill with red coolant or just run it as is and maybe DIY in 2 or 3 years. I only drive the car up to about 5k miles a year.
The car runs great. I have no leaks or cooling system issues at all.

 

[PandaBear]

They need 2 cooling system because they are 2 different temperatures. You don't want to overcool the engine or fry the electronics.

Inverter coolant doesn't come in contact with combustion gas leakage (head gasket will leak a small amount of combustion gas into the cooling system, enough to wear it out sooner but not enough to cause engine problem), so it doesn't wear out as fast.

 

[CR94]

What change intervals does Toyota recommend? Most Toyotas of that vintage (including my regular Prius) are supposed to use pink Toyota SLLC p-HOAT coolant or equivalent.

 

[Mr_Luke]

Originally Posted by CR94
What change intervals does Toyota recommend? Most Toyotas of that vintage (including my regular Prius) are supposed to use pink Toyota SLLC p-HOAT coolant or equivalent.


The manual says 100,000 miles for the radiator coolant and 150,000 miles for the inverter coolant.
I'm planning to drain it and refill it with Valvoline red anti freeze with P-HOAT. The manager of the car care place swears the Auto Zone universal coolant will be fine, and so does the person I spoke to from Auto Zone but the Valvoline red coolant is very close to OEM Toyota coolant and I might feel more peace of mind once I get it swapped.

 

[diyjake]

Definitely use Toyota or equivalent coolant, stay away from the universal crap.

 

[CR94]

Originally Posted by Mr_Luke
The manual says 100,000 miles for the radiator coolant and 150,000 miles for the inverter coolant.
I'm planning to drain it and refill it with Valvoline red anti freeze with P-HOAT. The manager of the car care place swears the Auto Zone universal coolant will be fine, and so does the person I spoke to from Auto Zone ...
Good plan. The Valvoline "Asian" stuff (and a few other brands) is a p-HOAT formula, therefore a legitimate substitute for the more expensive Toyota SLLC. I wouldn't trust "universal" mixtures pushed by a store that doesn't sell p-HOAT.

 

[Mr_Luke]

I drained and refilled both parts of the cooling system today and added new Valvoline red coolant for Toyota with P-HOAT. I got 2 gallons of it for $12.49 each.
There may still be a wee bit of the older coolant in the engine coolant side of it but I have a feeling it will be fine.
I drained 4 quarts & 24 ounces total out of both sides of the system, and I think the total system capacity is 1.25 gallons.

Valvoline / Zerex red for Toyota