Should I change or flush coolant?

IIRC the Owner's Manual says changing it at 10-years/100k-miles then average 5-years/50k-miles. Yours is overdue.

 

I recently noticed, in a Gen 2 thread, that what the 2008 Scheduled Maintenance Guide says about coolant is really kind of sneaky.

So I just looked in the 2014 Prius c Warranty and Maintenance Guide, and it's sneaky just the same way!

The charts extend to 120,000 miles and, in that whole span, the only place it outright says "replace engine/inverter coolant" is at 100,000 miles or 120 months.

They do, however, say to "inspect" the coolant, and that comes up every 15,000 miles or 18 months.

And every time "inspect" the coolant comes up, it is with a footnote number.

And on every page where "inspect" the coolant comes up with footnote number, there sure enough is a matching note at the bottom of the page:

- Refer to "Engine/Inverter Coolant" in the "Explanation of Maintenance Items" section in the back of this guide for more information.

And sure enough, there is such a section at the back, and the first thing it says under "Engine/Inverter Coolant" is to drain and refill it.

 

I don't know, I tend to stick with the Toyota stuff.

Personally, I don't end up following the chain of footnotes and changing the coolant every 18 months. I do like to dunk a test strip in it about that often, though.

That's more like what I would mean by "inspect".

 

I agree with ChapmanF, and I would definitely change it, as the additives that protect against corrosion are no longer able to do their job.

 

Yep I've heard that old coolant can cause the head gaskets to fail and I agree with previous suggestions, ONLY use Toyota Super Long Life....it's really good stuff! (I've used them all, in non-Toyota vehicles, and I'm most impressed with how well the Toyota SLL stands up over time.)
It is concerning that you notice the coolant level going down...might want to find a mechanic who has hybrid experience for a look over. (Might even be worth having a Toyota dealership look into it.) Better to pay a little now than a LOT later.
Keep us posted!

 

Your photo is of the reservoir for the inverter coolant. I've never seen the Prius c's inverter reservoir up close to see where the F and L marks are. They aren't visible (to me) in your photo but you should be able to find them. If it is a little below the F mark (but still above L), that's ok, though it would have been nice to leave it at F, which might require adding, like, two ounces more coolant there.

You didn't take a picture of the engine coolant reservoir. If a c is like a liftback, that should be near the right side of the car. How does that look?

 

It's just a little below the full line...if you have a bottle of Toyota SLL you could add a bit to it. It was, probably, filled when they serviced it and a little air was left in the system which worked its way out so that would make it a bit low. If you don't have any, swing by the shop and show it to them and I'm sure they'd top it off for you.
For folks who change their own radiator/inverter coolant in their hybrid, we are supposed to put the car in Maintenance mode and then let the engine run and top off the reservoirs while waiting for the radiator fan to come on and off two times.

 

On my 2022 Prius there are two lines on the bottle, marked min and max. As long as it is between those marks you should be good to go. Just keep an I on it for a few miles and don’t be surprised if it drops a little bit. If it stays too close to the min line for your comfort just ask them to top it off for you. I’d be surprised if they charged to do it but it shouldn’t be much.
Great job on making a wise decision!

edit: ditto on what Colorado said

 

No, that's the brake fluid. The engine coolant reservoir has the same pink stuff as the inverter reservoir.

With cars, when we say "right side", we mean right side of the car (which can be your left if you are standing in front looking under the hood).

 

OK, I kind of hate bringing this up but at157,000 wouldn’t both the engine, and the inverter coolant be changed, along with the brake fluid (especially considering the hi humidity of the Houston area and the age of the Prius)? With the care it’s been given considering the frequency of the oil changes, the car could easily get another 157,000 on it.

 

We should say...passenger side or driver side.

 

That actually changes more between countries.

It is a standard convention when talking about cars that left and right mean the left and right of the car.