Coolant level

check the o/m. see if that is appropriate when the engine is hot or cold.
you do need to be concerned about a potential coolant leak in the exhaust heat exchanger, so i would top it up if necessary per the manual, and keep a close eye on it, like every day.
coolant leaks can lead to head gasket failure, quite common on the early gen 4.
there is a tsb for the dealer if you find the coolant level dropping.

 

4th gen's with dropping coolant is often that exhaust heat recover system. Compounding that, dealerships may diagnose as head gasket failure (though protracted neglect of the coolant level may lead to that), and even if they find it to be the exhaust heat recovery system leaking, they may try to bill you, instead of Toyota. This could either be incompetence, or intentional, since the labour rates they can charge corporate Toyota are less than their retail customers. Best track down that TSB, bring it with you.

 

Welcome Knarff;
I would stop by a grocery store and buy a gallon of distilled water. When the engine is hot, top-off to max line. Check it every day or every other day for the next few weeks. The levels will vary a bit but it shouldn't go low again; if it does - it needs to be checked out. You can destroy the engine if it runs out of coolant.
As @Mendel Leisk stated; there's a TSB on this issue.

Hope this helps....

 

Or stop by dealership and buy a gallon of Toyota Super Long Life Coolant (pre-mixed).

 

Or just top off with the specified Toyota coolant. In the US, anyway, they don't seem to sell that except in 50/50 premix, which means if you have topped off with plain water, it's hard to get back to the intended concentration.

 

There should be an app or something for sharing partial bottles of coolant. I just topped up our Subaru, and I just changed the coolant in one of the Toyotas, so I have an open bottle of each type. If anyone's near Boulder, CO I'm happy to share.

I'd suggest aiming for halfway between low and full so it doesn't overflow when it warms up.

I noticed the same thing in my Prime around 60k miles. Both reservoirs were at Low when the car is cold. I topped them off since I have the coolant anyway.

 

Pretty sure 2016 is still a degas-bottle system like gen 3. Plenty of headspace in the bottle above the FULL line, and that is the target level after filling and burping.

The more pressing question is, did the old coolant go somewhere, and, if so, where?

 

Search this site for heat exchanger - you'll see plenty of threads on this issue.