System should retain 50/50 mix. If you're merely just topping off a bit, probably won't hurt anything if you just use distiller water. The more important question is why is your coolant low - sealed system with minimal evaporation.

 

I will check the hoses, I never had to top off the coolant before. Its about to hit low soon, so Ill call my mechanic and ask what I should do. Im gonna guess hes gonna say to just top it off with distilled as well. Just wanted to get other opinions from the forum

 

In the interest of only practicing good maintenance habits, I'd never add anything but properly mixed coolant.
If the reservoir is a bit low, and it's the first time that it happened, I wouldn't be too concerned -but would keep an eye on the level.
If the reservior is empty and the radiator isn't full, take it to the dealer for investigative service. An overheated engine is a very bad thing.

 

As long as there is visible coolant in the plastic bottle,, the main cooling system is full.

Hang in for next oil change, and specifically ask for tech to juice up the plastic bottle to the "F" line on the bottle.

 

You don't want to thin out the coolant. If you ever have to go over 50/50, you only do it with adding more coolant and not water. The mixture of more water will overheat faster and freeze faster. If you think you're going to add so little that it wouldn't matter, then don't add anything at all. As sbr711 said, the system is still full and as long as it's not low enough to catch air, it will be fine. No sense in thinning the whole system just to reach the line on the bottle. Pretty much, do it right or don't do anything at all.

 

Pretty much, do it right or don't do anything at all.

Wow - so adding distilled water is worse than not adding anything?

Being low on coolant is good?

 

I disagree with destro and some of the other guys here. Distilled water is perfectly fine for topoff and a 50/50 mix isn't really necessary. For most of North America 60/40 is more than enough. Interestingly a mix too high in "coolant" can cause a car to overheat and 50/50 is idiot proof. The water does the real work in cooling. Many performance and muscle car owners go to 80/20 or even 90/10 for this reason. If you don't believe me then research on your own.

 

Why is it that people come in with "race cars do it" or "Porsche does that" as if it applies to all vehicles. The Sonata is not not a muscle car and not a BMW, so because you can excuse a practice in one way doesn't mean you can apply it in another.

The coolant has a higher boiling point. While you don't want to put too much AF/EC in, 60% product to water is much better than a solution of 40%, in a Sonata system.

It is not just engine coolant, but antifreeze. He is in New York, in November, and I wouldn't want to do anything that would effrect the freezing temperature. While is probably would not get cold enough to freeze, why not buy the right stuff? $20 and you have a jug, if you were actually worried about it going empty.

 

haha I Still dont know what I should do... but I guess it isn't too big of a deal. I still have at least 3k miles left until next oil change. I dont think anything is leaking but will be sure to check the next time I use the car (which could be tomorrow or a week from now depending on the gas situation here in NY)

 

Top it off with Redline Water Wetter.

 

Just get a bottle of the pre-mix stuff and use that - what could be easier??

 

There are so many misconceptions and such bad info about this subject all over the internet. Rather than debate I will simply attach two pages from my 2011 Elantra manual. Sorry they are sideways, in adobe reader click view and rotate clockwise. Specifically check the info on the bottom right of page 7-23 and mixture % chart on the bottom left of page 7-24.

I suspect your Sonata manual has similar info

 

Colder the temps, the greater the the amount of EC/AF to water ratio. Same as I was saying. Nothing in the manual to state otherwise.