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Try Avi's Advanced Automotive, a member here.

 

It is a little harder to do properly than Inverter coolant. A complete change of the coolant requires opening the radiator petcock and also there's a drain bolt under the engine under the exhaust and a drain for the CHRS bottle. The car has to lifted pretty high to get under it in your driveway to get at that bolt and drains. The issue is like most modern cars air lock becomes very prevalent when you fill it back up as the engine is higher than the radiator.
Air bubbles get trapped in the cylinder head. Highest point. Complicated by the unusual addition of the Coolant Heat Recovery bottle compared to most cars. That tends to trap air too. Its difficult to bleed without having to trick on the CHRS bottle pump relay to circulate the fluid and the air lock.

This car is very easy on the ICE coolant. You did not mention the miles the most important factor but if there lower than say 125,000 miles a very good & easy way to attack this issue is just dump the rad by itself. Fill it back up with Toyota SLLC. Do this a few times and it will have a pretty good impact on freshening up the coolant. And you will not get airlock. Its a very small engine that is very easy on the coolant. Better than a full dump no but close enough. Especially if done once a year.

Dump it. Drive the car a few days and once in a while turn on the heat to circulate old fluid out of the heat coil under the dash. Dump it again. Do this like 3 times. It's a little wasteful but will have a great impact on the coolant system with little fuss.

You did the most important things the trans & inverter. Those are very hard on both the fluids unlike the ICE coolant.

Btw, if you do decide to do a full blown coolant change and your all the way under the car anyway that is the time to do some maintenance on the AC evap coil under the dash. Take advantage of raising the car!

This will keep the condensate dump hose clean & the e-coil under the dash from clogging. The dealers sells a 2 can kit with special hose for $25. that you shoot one of the cans a microbial foamy cleaner back up the hose. The foam fills the AC under dash e box and cleans it and then drips back out as liquid. Easy as pie takes 2 minutes and makes the ac & car interior smell 100% better. Keeps that hose from clogging which can cause alot of dama
ge if clogged. The hard part is getting under the car. At least for my old nice person.

Highly recommended especially if you smoke.

Good Luck!

 

Good. Its pretty easy and effective. Prevents the dreaded airlock which can be difficult.

 

I just did my radiator coolant change on my 2007 Prius with 125,000 miles. Have had it done at dealer before, but I'm almost sure they never did a complete drain and refill. It would take them too long. It's not too hard, but patience is critical both draining to get most out and refilling to avoid low level and overheating after. I've attached a pdf file made from a PowerPoint with photos and instructions. Let me know if you do it.

 

Its important to watch the level for a few days as any minor airlock will hopefully work itself out and that void will result in low coolant. Turn on the heat when car is warmed up and let the coolant circulate through dash heat coil. Should have max heat coming from vents. If not you have an airlock. If you hear any gurgling under dash or water running sounds under dash you have an airlock.

Most posters report "water running sounds" under dash. It's important you confirm you are airlock free becasue if it does have an airlock the car will overheat and you will never know it till it throws an an engine overheat dtc. By then its way to late as the engine will be severely overheated. Easy to damage aluminum cylinder head.

Sometimes a minor airlock can be fixed by jacking front of car up high as you can, taking rad cap off (not overflow but rad) and put car in inspection mode and let it run. Always topping off as level will bounce up and down.

Its a pain. Good Luck.

 

Good pdf btw.

 

Thanks. It took me longer to make the pdf than to do the radiator coolant exchange. I had to take off some parts a second time to get the photos I wanted of the CHS. Thank you for adding some tips I forgot to add about keeping the heat on high to get max flow through the heater core and avoid air lock and checking a few more times. I had done this even though it was uncomfortable doing so in JULY. I ended up adding a cup or so several more times myself over the course of the week after I changed it.

 

Good job. Its a pita.

The Inverter coolant change is cake comparatively. And well worth the time.

 

I'm about 2,000 miles away from that one. It was changed when Dealer did the warranty replacement of the inverter coolant pump at about 90,000 miles.
I did the transaxle ATF WS change not too long ago. That is pretty easy too. Hardest part is refilling, pumping the little pump I bought about 150 times for each quart. I opted for that rather than a funnel and long tube to refill since I did it by myself and wanted to avoid any overfilling and mess. That Toyota ATF World Standard is good, but expensive.
I did it at 123,000 miles.
Wish I had done it sooner, like at 60,000. Pretty dark and a fair amount of metal deposits on magnet of drain plug .
No problems with tranny, power and mileage got better. Attached a photo of tools, including a torque wrench, supplies and old ATF. Will probably try to do a pdf of that at some point.
I torque everything that has a specification. I had a bad experience when my son and I were replacing the seals for the plug wells on the underside of the rocker assembly on his 1992 Honda Accord LX. Special bolt, necks down at the cover. 10lbs torque on the valve cover. He gave it one too many tugs and broke it off. Special order, of course. Great result though. Stopped the oil leak into the plug wells. Old seals were so brittle they all just shattered when I took them out. That was 160,000 miles, now pushing 200,000. Even with the bolt, probably about $30 total parts vs. dealer $800.

 

Btw, doubtful they changed the coolant when they put in a new pump based on many reports here. Usually they just duckbill clamped the hoses and swapped new pump in. I can say with confidence if they did replace the coolant also the car would probably have to be there all day.

I would buy a gallon of SLLC and do it no matter what. The Inverter is the most important part of the car.
For you it would be easy. Dump and refill.
Pay attention to the level of turbulence in the reservoir between existing fluid and new fluid. The pump likes new fluid.

 

I checked my service records. Keep all the invoices. I had them change the engine and inverter coolant at 90,000. They actually gave me a loaner so they had it a whole day. I also had them replace the Auxiliary audio port under a TSB at the same time. They actually gave me a loaner so they had it a whole day. That's over 35,000 miles ago for the inverter and I know it's important, so I'll get it done. I already have the new crush washer. I may have a gallon of SLLC left. I already read up on the bleed procedures, so just waiting for the weekend. Let you know how it goes.

 

Thats good. I change my trans fluid and Inverter coolant every 30,000 miles. Which is about $60 every 2 1/2 years.