Question about engine coolant

Hi and welcome to Prius Chat. I suspect it would be better to do that in due course, because the genuine stuff contains corrosion inhibitors - maybe more than that! Others with more knowledge than I have will come back to you, so just wait awhile longer.

 

Welcome to Prius Chat .

Some questions:

• How many miles on your Prius?
• Have you owned it since new?
• Do you know why the reservoir got low and required fluid addition?
• Did you add distilled water?
• Are there any visible signs of leaks?
• What’s the color and smell of your engine oil?

Adding water to the coolant will change the profile of the coolants temperature range as it is now more “dilute”. Being in Montana, I would at a convenient time drain and fill the coolant.

Keep us posted .

 

The only reason drinking water might not be good would be depending on the mineral deposit level (Calcium, iron, etc) you could now have a source of “fouling” which could inhibit heat transfer in the case of calcium or a catalyst for corrosion in the case of iron. Distilled water removes that possibility .

With that low of mileage, The reservoir could have been filled low when the previous owner had it and they just never checked.

I’m not sure if in Montana you would have the more concentrated blend of the SLLC or not. Canada and Alaska do as it gets cold there so the amount of ethylene glycol is higher .

So if you have the means and ability, I’d stop by or call the nearest Toyota dealer and ask them what concentration is used and swap it out.

Keep us posted .