platinums get a resounding booooooooo from the peanut gallery.
I think he was saying that after 3 years, changing the plugs created such a noticable difference that it felt like a performance modification compared to before. Which means the interval should definately be less than 3 years.
Damned metric system... I change my plugs every 50k km (50 Mm?). NGK coppers, heat range 6 last time... probably going with heat range 7 next for a colder spark.
-Chris
91SS 4EAT stock, 200k mi
91SS 5MT rebuilt engine waiting for a shell
93TW 4EAT, Forester lift, 3" TBE, 11psi, 200k mi
94SS 5MT4.11+rLSD 311k km: RobTune550,TD05-16g @ 18psi,FMIC,3"TBE,Forester lift