According to the shop manual for the six speed automatic transmission, approve AT fluid is Hyundai Genuine ATF SP-Ⅳ, ATF SP-Ⅳ SK, ATF SP-Ⅳ, MICHANG ATF SP-Ⅳ, NOCA ATF SP-Ⅳ.
Quantity for a full replacement is 7.08 quarts, kind of question that extra 0.08 quarts, that would be a complete drain.
On most other vehicles, want you to remove that top plug when the AT fluid is cold, so if they check it at the shop and its hot, going to lose some, AT fluid has a high expansion rate. Hyundai recommends it be checked when hot.
Heard people say the reason why they eliminated the dipstick is so people won't pour windshield washer fluid in, that would be a heck of a chore because the diameter of that tube was very small. Also a pain in the butt to add around 17 quarts to it through that little tube. But for years, like Ford and GM, replacing just the filter and about four quarts was required, recall paying 30 cents a quart.
To replace all of it, had to remove a cooling tube, run the engine and pump it out.
Ebay has some nice prices for Hyundai Genuine ATF SP-Ⅳ. but since this is a combustible fluid, would cost both arms and a leg for shipping. Would haggle with your dealer. Did that with oil filters, less than four bucks each.
Hondas was easy, every 30K miles, had a cap on the top of the AT with a dipstick on it. Recall it took four quarts, genuine Honda for a buck a quart and did that at the same time as changing the engine oil.
Removing the engine undercover was always a pain, replaced all the screws with stainless. Weren't metric, but who gives a darn. Crap in there rusted tight.
Could be old fashion, like to see exactly what comes out of there and exactly what goes in.