I have 277K miles on my 2003 QX4 and making an effort to fix all the oil leaks. valve covers done, oil cooler done for the second time. next is the rear main seal. I noticed a plug with the hex socket on the bottom of the engine near the oil pan. Can anyone tell me what this is? Is may have a small drip and is there a gasket behind the plug?

https://imgur.com/a/sJICkwH

Can't remember off the top of my head if that's an oil gallery plug or if it goes to the water jacket.

Either way it's likely sealer with an aluminium crush washer like all the other large plugs like that.