Virtually all modern anti-freeze is ethylene glycol and that is the component that changes the freezing and boiling points. The only difference is full-strength or pre-diluted as far as that part goes.

The tricky part is the anti-corrosion chemistry. There are various types and various additives. If you change every 30k, you really shouldn't have to worry too much. Hyundai recommends changing after the first 60k, and every 30k there after. On my sons '08 accent, I added less than a quart before the 60k change. I just made it up with distilled water. It still shows as good to -30°F on my float checker, so that was fine.

The important thing to understand about anti-corrosion tech is that they are antagonistic. If you mix an Asian p-HOAT with a euro whatever, the mix will be less effective than either one. So just use distilled water to make up small amounts. If you need a lot, a) you have to find out why, and b) you are better off adding in OEM coolant from Hyundai. You don't want to use pure ethylene glycol and water because that means no anti-corrosion and that is a bad thing.

For the 60k change together with the timing belt, I used Zerex Asian Formula. It is compatible with the Asian motors and avoids the silicates and borates that Asian engineers disdain. And it costs less than OEM. The disadvantage is that it is pre-diluted.