Since our vee-hi-cules are no longer spring chickens, make it a point to be more diligent in the thoroughness and frequency of your system checks. I was recently rather lucky when a scheduled brake job being done at a friend's place revealed a pin hole leak in one of the brake lines, and my friend, talented as he is (restores pre-war Mercedes), spliced in a new section for me (I don't want to guesstimate what the dealer would have hosed me for). We couldn't detect any obvious problems with the other brakes lines, but the fuel line at a metal connection was showing considerable corrosion.
This prompted the whole question of completely replacing all those lines, which is a mega-job, in that the fuel tank has to be removed to get access to the lines which run over the top of the tank, and removing the fuel tank means removing the exhaust system, then removing the drive shaft, then removing... you getta the picture. It's not impossible, just long and involved, a project necessitating several six-packs, if not a keg (if for no other reason than to preserve a friendship).