For those of you using these spark plugs, what replacement interval have you chosen? I have roughly 40k on my plugs but I also notice a slight miss at idle. Check engine light came on while driving but went away the next day. I will get codes read tomorrow and post what I have found.

 

Somewhere between 80,000 and 100,000 miles.

 

go autolite cheap and they work great...

 

Wow, 80-100k..thats good. I may go cheap plugs next time. I don't think I notice any performance difference between the originals vs Iridiums other than the long replacement interval.

 

I picked up +4's at RockAuto for $4.70 each- thats pretty inexpensive considering the quality of the plug.

 

Dont go by miles, go by what the engine tells you.
If you notice a little rougher idle, check the plugs for gap or carbon.
Iridiums are supposed to last 60k+.