Kidding! Regular plugs require to be changed about every 30-50K kms. Platinum plugs every 90K kms and Iridium plugs every 150K kms. It is just the material that the electrode is made from. Every time that the spark jumps from the electrode to the post, it takes a few minute particles with it. Iridium is incredibly resistant to this stress and just last longer. That being said....I would not want to pull the plugs out of an engine that has had the plugs in for 7 or 8 years. Can we say seized?
Hope this sheds light on it.
1992 Bonneville SSEi
White, grey Leather interior.
Tinted windows and blackouts on headlights.
Custom high flow exhaust, Everything replaceable - DONE
300 000 kms original engine, tranny 2 rebuilds.
Playboy Bunnies Embossed in Tint. Oh Yah!
Ever Seen a Polar Bear in a Snow Storm?