How do I do a auto transmission fluid change

CAUTION: CHANGING THE TRANS FLUID MAY KILL YOUR TRANSMISSION IF IT HAS NEVER BEEN SERVICED. AS ODD AS THIS SOUNDS, IT COULD BE SURVIVING ON CLUTCH MATERIAL IN THE FLUID! If you change it and the car no longer shifts, your trans is cooked. SAVE THE OLD FLUID IN A CLEAN BOTTLE, SHOULD IT BE WHAT WAS KEEPING IT ALIVE! I am not kidding. Outside of Aisin transmissions, not changing the fluid on a neglected transmission is the best thing you can do.

Given this is an older car, you can usually fill these from the top as they could be refilled from the engine bay - that said, some early 2000s cars did move to the current drain and fill process where it is done from the bottom.

If you take a look at the SM for your Rio, I did find it has the bottom drain design so you may have to put your car on jack stands and lift it a few inches to get to the drain plug. Here is where it is on yours per the SM:

KIA RIO 2005

KIA RIO 2006

KIA RIO 2007

KIA RIO 2008

KIA RIO 2009

KIA RIO 2010

KIA RIO 2011

NOTE: I am looking at the 2011 SM, so while very unlikely due to EPA and other 3 letter agencies, there may be differences. Post the MY and we can better locate accurate service information.

In your case, the SM does not indicate how much trans fluid you need :-(. Based on some quick research, it is allegedly 6.4 quarts, but other sources https://Like this Kia Forms post indicates 7 quarts. Your best bet is to measure the fluid that comes out and see, but if my guess is anything to reference the tans is likely 6.4 quarts or 7 quarts.