I used the ultimate solution. Stage8 fastener. No way they could ever come off.

http://home.att.net/~benmlee/stage8/stage8.htm

Even with locking fasteners, those round gaskets tend to get compacted over time, then they leak again. You have to re-tighten new ones once the engine warms up and cools down again. I would check tightness a week latter. Check again a month latter, then 6 month etc. That is the only solution I have come up with so far without also going to braided tube.