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As far as I know, all the hoses on our coach were original to its manufacture date - 2003. A few years back, we had a coolant hose with a small leak. It was replaced in Las Vegas. I had planned to get all the hoses (oil, coolant, air boots, etc.) inspected then, but forgot to schedule it. My guess is that exposed hoses should be inspected every five years or so, and replaced at 15 years just because they're old.
In my prior message on this thread, the tech's total mileage was 282; Payette is about 86 miles from Jordan Valley. At $2.50 per mile; that's nearly $700 for all the miles. The labor charge was $175 per hour for 7.5 hours... 5 of those 7.5 hours were travel time!
As I said, get out the credit card!