Has anyone ever seen this done before? It looks like someone drilled in to the freeze plug and then plugged it with some sort of rivet and rtv. I've never seen it before and I dont know why they would do it unless they ran out of freeze plugs. Can someone explain this. Please dont tell me to ask the machine shop. Its not an option. Thanks.

 

Laziness IMO

 

I just posted the same question on z31.com and someone said it was a "heat tag". They say it's to tell if the engine was overheated for warranty purposes. I guess if it gets hot enough part of the metal in the middle or something melts and they can tell. Makes sense to me so I guess its not something stupid at all. Interesting.