Valve seals obviously wear out over time. A very common way to tell if your vavle seals need attention is the car will smoke - but typically not all of the time, just after you sit and idle, say at a stop light, and then you get a puff of smoke when you start to drive again. These are replacement valve seals.
Valve Seals - Set of 24 (3000GT / Stealth DOHC) Valve Seals - Set of 16 (2.0l Turbo DSM / EVO) Valve Seal - Individual DOHC or SOHC
We have double checked with our supplier on these and we can confirm that these are Viton seals and not Poly-acrylic like the OEM valve stem seals are.