Iridium is said to be six times harder and eight times stronger than platinum. This means that spark plugs can have even finer electrodes than ever before and still have excellent wear characteristics. Platinum is precious enough, but iridium is even more precious, which is why it is hard to find a single platinum plug for much under $6-$8 and an iridium plug for under $12-$14.
Is it worth the extra cost for platinum and iridium? Yes and no.
If you are willing to change your plugs once every year or two depending on your driving habits (and it is actually quite easy to change your spark plugs), copper plugs can offer good performance and efficiency. It is also worth mentioning, that with platinum and iridium plugs you generally get what you pay for.
The more expensive the plug, the more platinum (double/triple coated) or iridium is usually used in the plug. A thin coating of these precious metals will not fair as well as a thicker, so in general, you won't want to go the cheap route, as it would be better to just use good old copper for your maximum value.
However, in general, the standard copper plug does not reduce quenching like many of the platinum and iridium plugs can. With this said, technology has opened copper type plugs to the similar benefits of the fine electrode using various configurations and shapes. This is where the specialty plug comes in, such as the U-groove or Splitfire.
There is much controversy over the benefits of such designs, but we will cover the most popular ones as well as discuss their potential and ability to perform as they have claimed in part 2 of this series.
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