How do you know this, Andrew? Do you have any statistically significant information that says many people swap out their iridium plugs before they need to? Is that a majority of the folks who buy these plugs, or only a fraction of the folks? Or are you basing that statement on some anecdotal evidence that John Doe posted in a thread and echoed by Al Smith?Except that many people who buy them do not use them for any where near 5 times as long so they are not benefiting from that benefit if it exists, which was one of my points in my earlier post. I have many times read of people who install iridium spark plugs in their ST1300 because they desire what they perceive as a superior spark plug and the increased change interval that they offer. They then replace them them at 24,000 mile intervals happy that they have extended the Honda recommended change interval by 50%.