Once you clear 100k total miles, if you have a notoriously picky transmission (especially if fluid changes are easy), I would up this to 30k fluid changes. My Odyssey is one such beast with tons of trans issues, so every other oil change (around 20k or so) I drain what comes out and refill with fresh fluid; about 3.9 quarts.
Generally, most manufacturers recommend a transmission fluid change every 30,000 to 60,000 miles. But with automatic transmissions, figuring out when you need a change can be more challenging. In that case, don’t wait for leaks. According to Hyundai, your car’s transmission may slip if you don’t frequently check your fluids at least everyStep 3 – Drain the ATF fluid. The drain plug is a 3/4-inch square recessed head. You can use a 3/4-inch drive ratchet without a socket attached, or a 1/2-inch or 3/8-inch to 3/4-inch socket adapter to remove it. The drain plug is found underneath the transmission on the passenger side.
Pour in 9 quarts of automatic transmission oil, one directly after another. Remove the funnel. Push the dipstick all the way into place in the tube. Check the fluid level with the dipstick. If it reads low, you can add ⅓ quart of transmission fluid at a time until it shows full on the dipstick. BzFulbH.how often to change automatic transmission fluid
