Down here in Florida you can expect standing 1x19 wire to last about 10yrs before the terminal swages begin to show cracks. Cracks generally show up at the bottom swage before the top...water stands there. Some experienced sailors swap ends every season to lengthen the life. The rigging shops used to tell us to change wire at 10yrs regardless of what it looked like. I have personally witnessed wire that looked perfect (bright and shinny) on a Pearson Triton sloop and it broke strands when we took it down and coiled for storage...wire gets stretched and brittle over time. I watched several old time cruisers take their standing rigging down once a year and wash with detergent and fresh water. Then soak the terminal ends in pure lemon oil...without additives. I never tested this but it was done frequently in the yard I was berthed in Ft Laud. The swaged ends will also let go before you see any cracks...this has happend to me on two boats with unknown age of rigging...one had rolled swaging and the other nicropress. Lower shrouds usually go first. Bill P.