Toyota Repair: Valve Stem Seals - Camry, frequent oil changes, recommended interval

Question
Ted, what's the life expectancy of 2.2l valve stem seals?  What's recommended maintenance interval?  I've got two Camrys.  A 99 and a 96 (both 4 cyl) and just did the VSS at 92k.  The 99 has 134k and haven't been done, but there's no smoke at startup and no oil loss between changes.

Answer
It depends a great deal on maintenance, frequent oil changes will keep the seals soft and they will continue to seal, lack of oil changes at regular intervals will make the seals become hard and stop sealing, there is no recommended interval to replace the seals, it is fairly common for the seals to start leaking at around 80,000 miles causing blue smoke at startup mostly on cars using the 5SF-E 4cylinder or the V-6 but almost always on camrys and RAV-4s.