When doing an engine and inverter coolant change, you use the same coolant?

Yes, it's the same coolant in both the engine and the inverter. I know it's expensive, but it requires changing so infrequently, I just go with the OEM Toyota coolant.

 

www.amazon.com/Toyota-Scion-Coolant-Antifreeze-Genuine-00272SLLC2/dp/B018Y2WQRK
2 gallons, $50

The engine loop may use 7.6 qt
The inverter loop may use 2.2 qt

 

I used the same coolant to change each of them two days ago. The process was quite easy and took a total of 1.5 gallons. I changed the transmission with Valvoline Maxlife, inverter and radiator with Zerex Asian, and the oil with Mobile1 fuel economy 0w-20, all at the same time. The total fluid cost was $75. With mileage at 59,000 miles, the transmission fluid was black and well worth changing.

 

If you haven't already, watch @NutzAboutBolts video, for both engine and inverter coolant circuits:

Nutz About Bolts Prius Maintenance Videos | PriusChat

Regarding the fluid to use: you may be ok with what you have, but carefully read the requirements in the Owner's Manual. If you're missing the paper manual you can download pdf format at Toyota Tech Info, Manuals section. Safest is to use what's spec'd in the manual. Here's a screen grab:



Also, here's a couple of excerpts from the Repair Manual:

 

The big cost difference is not with the coolant itself.......but with the "backflushing" that the dealer recommends at a HUGE markup.
That part really doesn't need to be done unless there is some evidence of blockage.

So....unless you just like the challenge, ask the dealer what they charge to JUST change the coolant. You might be surprised.

If you do it yourself, use long life coolant and mix with distilled water; NOT tap water and NOT filtered drinking water.
Easiest thing to do it buy "pre-mixed". A bit more expensive but much easier to deal with.

 

The Toyota Super Long Life Coolant comes premixed. If the dealership is following the Repair Manual (attachment above), they will pretty much just drain and fill.

 

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