The drain plug on most 2015 Kia Optima models uses a 14mm hex head, so a 14mm socket or wrench is the standard tool. This applies to the common engine options for that year. Use the correct size to avoid stripping and replace the washer if applicable.
The standard size you need
For the 2015 Optima, whether you have the 2.4L Nu engine or the 2.0L Turbo, the oil drain plug head is 14mm across the flats. This aligns with factory service specifications and typical aftermarket parts. If you don’t have a metric set handy, a close SAE option like 9/16 inch may fit imperfectly and risk rounding, so aim for 14mm when possible.
What to have ready before you start:
- 14mm socket or wrench (preferably a 6-point for better grip)
- Oil drain pan to catch the used oil
- New crush washer or gasket for the drain plug
- Ratcheting wrench or breaker bar for extra leverage
- Appropriate oil for your engine type and a new oil filter
Having the right tools helps ensure a clean, efficient oil change without damaging the plug or pan.
Engine variants and cross-checks
Although the vast majority of 2015 Optima models use a 14mm drain plug, some dealership or aftermarket plugs may have different head types. If you encounter a plug that does not fit a 14mm tool, double-check the head style and refer to the owner's manual or service information for your exact engine code (2.4L Nu or 2.0L Turbo) to confirm the correct size and installation procedure.
Summary
Bottom line: use a 14mm wrench or socket for the 2015 Kia Optima oil drain plug. This covers the main engine configurations for that year. If you see a different head, verify with official documentation before forcing a tool onto it.
What size is the oil drain plug on a 2015 Kia Optima?
Dorman – Standard Engine Oil Drain Plug: M14-1.50 Thread, 17 mm Head, 1 Clamshell/Card (Part No. 090-033CD)
What size is a Kia oil drain plug?
17 mm
Dorman – Standard Engine Oil Drain Plug: M14-1.50 Thread, 17 mm Head, 1 Bag (Part No. 090-033.1) This engine oil drain plug is designed to match the fit and function of an original equipment plug on specified vehicles. It is engineered to replace a missing or damaged plug and help ensure a secure seal.
What size socket does an oil drain plug use?
System works with any 3/8'' drive GearRatchet or standard 3/8'' drive ratchet. 6-point sockets are magnetized to retain oil drain plug.
What size socket for Kia Optima oil plug?
All plugs have 14mm hex – just one wrench works for all.