[mustang67408]

Word of warning : If you change the INVERETER COOLANT. BE CAREFUL to make sure the system is bled of all AIR POCKETS. I usually drain the system, fill it, let it run for 15 minutes (switch on , no ready light- this runs the inverter coolant pump) check the level in the resovoir and open the air bleeds to allow trapped air to escape. I continue to do this for 1- 1 1/2 hrs. Then give it a good roadtest and check for air 1 last time.
If the Inverter overheats, weird things start to happen.
Please use only the Toyota recommended coolant, its premixed.
If you use something else and dont get the mixture correct it will cause other problems, such as overheating the inverter.

Personally the Toyota stuff lasts along time in the inverter, it basically just circulates and only gets hot from electrical components, unlike the coolant in an engine that takes alot more abuse.