Unaging virtue and Aging

I seem to be suffering a brain-fart or early alzheimer.

Where is the rules for how the Unaging minor virtue affects Aging?
You never gain any apparent age I seem to recall, but then how do you know you are ready to die of old age?

Thanks in advance

Reading the Virtue's description, my interpretation is that you make Aging rolls and accumulate Decrepitude points just like everybody else - it's just that, if something bad would have normally happened as a result, it doesn't happen to you. (Except death.)

Right - it's "all or nothing". The character rolls as normal, but if an Aging Crisis appears, there is no tangible penalty (unless the Crisis = "Fatal), but Decrepitude Pts are gained as normal - they just have no effect at low levels. When the character gains 5 DP, they die. So they know it's on the horizon when they have 4 DP's (but the Fatal crisis is always a small possibility, just as for anyone making any Aging roll).

(The only "rules" are those under that Virtue, afaik, p 50.)