Lycoming specifies allowable sealants. They are not allowed to experiment in the aviation industry.
We can be more freewheeling. At this point I don’t think anybody would us an RTV sealant on a Porsche case. Loctite 518 probably would not respond well to a thread in it. It is a pretty thin coating.
https://www.lycoming.com/sites/default/files/attachments/Alternator%2520Crankcase%2520Parting%2520Surface%2 520Sealants.pdf