1UZ valve stem seals: at what mileage did yours start going, and how did you address it?

[lexboosted]

The valve stem seals on these motors harden with age, and you start seeing the classic symptoms: occasional smoke on cold startup, gradual oil consumption that gets worse over time, sometimes oily plug threads. It's not catastrophic but it's annoying and it's incredibly common on high-mileage 1UZs.

I want to collect community experience on this in one place since I don't think we have a good reference thread for it.

Three questions:

1. At what mileage did your 1UZ start showing valve stem seal symptoms?
2. Did you fix it (heads off, seals replaced), live with it (thicker oil, regular top-ups), or wait until something else forced the issue?
3. If you fixed it, what did you learn that would help the next person?

Whether your car is at 80k or 300k, the data point is useful.