Hi Scotty.
Just installed new Iridium spark plugs for my 2003 Corolla LE. 105,800 miles on the car. Second hand car, unknown miles on the old plugs, could be factory original.
How long are they supposed to last? I've seen anywhere from 30,000 to 120,000 miles.
Thanks. P.S. the old ones looked ok, no oil or burned marks.
I’d replace iridium plugs every 100k mi.
With Iridiums, 100k mile intervals are fine. Obviously if you have an issue before then, you want to check them as normal but 100k is my change interval and I've had nearly no premature issues with them.
I don't trust any spark plug past 10,000 miles and I don't care if it's made out of UNOBTANIUM.
10k miles?
they definitely last more than 10k. Mine were still working great at 170k
Yes, 10,000 miles. Spark plugs still require a 25,000volt current to jump between two contact points, and corrosion occurs. The corrosion causes higher resistance and less efficiency thereby necessitating replacement for maximum efficiency.
Ummm ok that’s a very short change interval but I’m sure changing them out that frequent you’ve never had any issues with plugs though.
it just needs to ignite the fuel mixture
@mountainmanjoe 👍
That’s overkill, I usually go a minimum of 100,000 miles on Iridiums without issues on all my vehicles.