@Jokey_Carrot But why a Pi of all things?
I still don't think it's worth the hassle just for a Pi. I can see why you'd want to do it to a desktop PC though (but my answer would still be don't, although for a different reason, it's incredibly messy whenever you want to change out parts or add new parts, or you need to take it apart for some other reason, and also any parts that aren't cleaned off immediately after removal will then start sucking up dust and you'll get a crusty layer of dust that's almost impossible to clean)
Mineral oil might look cool but it's not worth it. Trust me.