Oil drain bolts on most vehicles vary from 7/16 to 5/8. Take a crescent wrench under with you to check, then compare the size to a regular socket and use it.
If it's the "oil" drain plug, the size wrench is, better yet use a socket wrench=13mm.
17 mm socket or boxed in wrench.
Probably about a 15 millimeter wrench or socket.
If the drain plug is original equipment, it takes a 17mm wrench or socket.
18mm
17mm socket will work fine
a 3/8 ratchet w/ no socket, its on the bottom of tranny and refill on top of tranny w/ 17mm socket on the bolt that has ATF stamped in it.
An adjuster bold wrench does wonders....
15 mm
It'a 7/16 bolt on that car.
Use a proper size box-end wrench or socket to remove the oil drain plug
The 2002 Kia Rio head bolts can be removed with a 12 pointed 12mm socket