We put a new 0-320 in our club 172. On first annual I helped our A&P with the engine portion. I noticed that the tube was loose and leaking, I grabbed it and hand tightened it. He said it was not worth the effort to torque and re safety wire. Later at OSH I talked to a guy at the LYC tent, he told me that it would come loose twice, just to retorque, re-safety and after the second time it would not leak again.
I don't know if this is fact or not. Some of the long time Lyc guys should confirm, but that is the story.
I hate leaks and plan to address each one to keep the engine dry.