Are Iridium spark plugs worth it?

I had them in mine for about 50,000 miles and had no problem and didn't see any performance benefit. I did go back to copper, but more because of the fear based on this forum. Will I go back, will see when the time comes to change. It is my opinion the longer you leave plugs in without changing them, you increase risk of having trouble removing them and sometimes damaging the cylinder heads threads.

 

We're so spoiled. 1954 bel aire required spark plugs be changed every 10k miles or 12 months.. whichever came first. https://myenginespecs.com/chevrolet/1954-chevy-235-engine-specs-configuration-and-service-intervals/ ... meanwhile our OEM Denso coppers are rated for 30k miles (and usually can be taken up to 45k miles comfortably.. lol). They're also pretty cheap and easy to do with the right tools

 

Unleaded gas really helped plug life.

 

AND our overall health! Imagine sitting in traffic in a city during gridlock in the mornings/afternoon commute with leaded gas? Terrible..

 

The other issue with running some plugs way beyond their suggested life is when the tip wears the gap increases, increased gap makes the coils work harder, heat up more and the potential for a coil failure goes up as gap increases. At some point coils will attempt to spark out the side of the coil through it's insulator to the valve cover, once that happens there's a misfire path and the coil is shot. This is a typical coil failure and it doesn't take large gaps to occur but excessive gaps tend to accelerate the process and often expose age related weaknesses in the coils. Once a coil goes bad any economy resulting from one type plug vs another is gone. If one doesn't want to change plugs as often iridium is a better choice since their electrode is much more resistant to electrode wear and gaps are more stable over the long term.

 

OEM plugs went over 200k for me, so i put in stock oem plugs for the next 200k