Oil pan plug size on 2006 Buick Lucerne

I am trying to determine the exact size of wrench that will fit the oil pan plug on my car. One 14mm socket fits it, but a 14mm open/closed end straight wrench is too large. What is correct?

Asked by for the 2006 Buick Lucerne
Some show 13mm and some show 14mm use the boxed end as long as its snug it will be fine.
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Using a wrench a 13mm will fit it.
13mm seems to fit pretty snugly. No room for a drive though, just use a box wrench.