Yanmar Oil Sensor Removal

[Shorty]

I will be adding oil pressure & water temp gauges to my 3GMF. Anyone know what size/type wrench is typically used to remove the existing oil sensor shown below? The boat is in Maine, 350 miles from home, so I like to be prepared when I head out to the mooring, far from any stores.
The hex seems to be 27mm or 1-1/16" across but the points are dimpled in. It looks like the dimples might accept the points of a 12 point socket, but then the question is what size & does it have to be a deep one? I haven't tried it yet so perhaps channel locks will get it fine but I do like to be prepared when tackling these projects, so as not to spend all my time chasing tools.
Thanks!