Goedel machines (that prove that the next step is better) try to use maths as an oracle. Which relies on the mathematical foundations being true. Other oracles I've theorised could help are oracles from the future that can say whether the change detaches the system from reality or not, a sort of go/no-go signal for potentially detaching changes.
Are there any other classes of oracles?
There might be some complex quantum computation that I'm not thinking of, due to classical computer bias.