I was just looking on O'Reilly's for a drain plug for my 2015 Jeep Patriot sport 2.4 l and some of them have a 16 mm head on them and some have the 13 mm head on and the one that is currently on the vehicle is 13 but they are out of stock on the ones that are 13 are the ones that have the 16 mm heads interchangeable with the 13 any help much appreciated