Anyone else try or use Iridium plugs? I put some in about 36,000 miles ago. I did so based on claims by some of improved fuel economy. I saw no improvement at all. I pulled the plugs today to check and see how they were doing. I checked the gap. They had all consistently opened up .020 inches. IN 36,000 miles?! I'm thinking I'll put the four pronged plugs in. These plugs don't seem to hold up or provide any mileage benefit. Thoughts?

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