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How Long Do Iridium Plugs Last?

September 30, 2012

A traditional IX iridium plug such as NGK ZFR6FIX-11 has an iridium center electrode, however the ground electrode is a traditional nickel construction.  Therefore, the ground electrode will wear out first. NGK gives them a life expectancy of 40-50k miles.  But they have to temper their projections as driving conditions and motor modifications differ.  Typically we have found you can expect 60,000 to 80,000 miles on an unaltered motor.



NGK Laser Iridium plugs have iridium center and a platinum ground electrodes. If installed in a regular engine, they would likely last longer than most people keep their car (barring any motor problems that can cause premature plug death).  All Laser Iridium plugs are an OEM design, made for a specific engine.  Some feature a special resistor or electrode design, depending on the OE requirements.  In their OE application, NGK's Laser Iridium plugs typically last 80-100k miles.


Andrew Fabian

Feb. 12, 2015
We were running upto 20 lpg vehicles and finding standard plugs and some more special ones were lasting 5 to 10 thousand miles and suffering misfires, my search ended with iridium plugs and as yet had no misfires , also I decided to change a set on a jeep Cherokee because of electrode wear after 138 thousand miles, this is the first set I've changed, as you can imagine I am soo impressed 😄 NB this has been at least a ten year excersise 😄


Jan. 3, 2015
Best plugs you can get. However, don't take the mileage frequencies for granted. I just had one of the laser iridium plugs fall apart (ground, node, and some of the ceramic casing) and go flying into my 3rd cylinder chamber causing a misfire and a lot of worry @70k miles on them. Be safe and not sorry and replace them every 50k miles if you drive a vehicle meant for performance, even if it is OEM and not tuned.

Wade Allen Hawk

Sep. 2, 2014
I bought a 2002 Mitsubishi Mirage and it had "I think" 27k miles on it when I bought it, shortly after I bought it I changed plugs and installed NGK. Right now there is almost 127k miles on the car and now my gas mileage finally started suffering. I just ordered another set. I am amazed those plugs lasted this long with me driving that car. Most of the time I drove it like I just stole it, and to get 90k out of a set of plugs is amazing. I wouldn't think about using anything else in my Mirage, the price of these plugs is justified IMHO. Keep up the great work. I would rate these a 10 out of a possible 5 if I could.


Feb. 25, 2014
OE Ford f-150.....209k miles original plugs!

Electrician by day mechanic by night

Nov. 1, 2013
NGK makes probably the best spark plugs in the world..they last we'll into 100k miles in a normally operated engine..the only problem with all spark plugs is the performance of the spark is reduced with even though your original plugs still continue to work in your vehicle with over 100k miles, the efficiency of the engine is not the's a good idea to check the spark plugs every 80-100k miles
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