What is the drain plug thread?

[XMES RUS]

I understand my drain plug thread has a hair line crack and is leaking oil, can someone help to explain what and how this would happen, and how this would be replaced/cost?
Thanks

[davemac250]

Do they mean the thread in the sump drain hole or the thread in the plug?

In the plug, pennies, get a new sump plug.

If it is the sump side then you may need to look at a new sump, maybe you could heli-coil it.