1. You can't get away without rubber.
2. One failure of steel in almost 60 years actually proves the reliability of steel. The one failure would have to be analyzed to see if is was steel fatigue, corrosion, embrittlement or a cause unrelated to the material.
(1) Actually you can get away without rubber. The copper was formed to have a "vibration loop" in the old days, and it worked well. Of course, not as many miles were driven. Rubber is more practical today than the vibration loop, but rubber is the weak link in the system (except for the folks that use clear plastic).
(2) In the same time period, ZERO failures from either copper or aluminum (I have a lot of aluminum lines, as well as some copper). Have never used brass. The factory steel line broke at a flare. Again, simply pointing out that the copper and aluminum are reliable.
Jon.
