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Difference Between Iridium and Platinum Spark Plugs

Iridium vs Platinum Spark Plugs

Aside from the very common copper spark plugs, there are two other options for most users; platinum and iridium plugs. Both types have the very same parts and construction, the only difference between iridium and platinum spark plugs is the metal used for the center electrode. As you may already have figured out, platinum plugs use platinum while iridium plugs use iridium for the tip of the center electrode. Iridium plugs cost more than platinum plugs, partly because iridium is a rarer metal than platinum, but also because it offers several advantages.

Iridium has a much higher melting point than platinum; with values at around 4400 and 3200 degrees Fahrenheit respectively. Iridium surely has an edge when you consider that gases are constantly being ignited in the chamber, exposing the spark plug to very high temperatures. The higher melting point means that iridium plugs can be made hotter than platinum plugs. Although hot plugs are not always desirable, it is preferable for city driving.

Another advantage of iridium over platinum is strength, with over 8 times the strength of the later. This essentially means that an iridium spark plug can take a whole lot more punishment before experiencing significant wear. A platinum spark plug is expected to last for 60 thousand miles before needing replacement while an iridium spark plug can go for 100 thousand miles or even more. The cost of the plug many not be such a significant argument, but the actual replacement can be an issue for some vehicles. Spark plug locations may be difficult to reach or require that other components be removed first. It would be more difficult if you do it yourself or more costly if you have it done in a shop.

Difference in performance would be relatively small if any between iridium and platinum spark plugs. If you are considering either as a replacement, the iridium plug is probably better since you do not have to change as often and you do not have to worry about the electrode prematurely eroding inside the combustion chamber and possibly leaving harmful deposits. But if you like changing plugs often, as new plugs would always perform better, using platinum plugs may not be a bad idea.


1.Iridium and platinum spark plugs have different center electrodes
2.Iridium plugs have a higher melting point than platinum plugs
3.Iridium plugs are stronger than platinum plugs
4.Iridium plugs last longer than platinum plugs

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  1. I have a 2001 Buick Park Ave. and replaced the Iridium spark plugs with Platinum plugs and see no difference in performance or mileage. I change my plugs every 50,000 and have had no problems. I switched because of the cost and more importantly the length of time the plugs are installed. The longer the plugs are in the engine, the harder they are to change and more likely they will seize up and break when replacement is necessary.

  2. Use anti seize Bob. I’ve had my plugs in my 5.9 Durango for over 100,000 miles and they came out like butter.

  3. There must be some benefit gained by the Irdium series of spark plugs, since so many are supplied OEM on the vast majority of new cars(requiring an initial plug last ~ 100K miles)

    NueView Headlight Restoration

  4. Got 91,000 miles out of champion copper core plugs 16 of them on a 04 ram hemi engine also use antiseize, i didnt on first replacement at 65,000 and those plugs came out but some of them were difficult so the antiseize went on new champion copper core plugs today, truck pulls like it supposed to and runs supremely easy very light throttle maintains speed 70 mph nothing to it, just needs some paint and keep on truckin!

  5. I have a 2008 kia spectra with 134,500mi and had the plugs changed at 106,000mi. Was advised Iridium plugs were better, so had those put in.
    Now at about 134k no the plugs are trashed. Had everything in the motor diagnosed. Changed over to platinum plugs and cold starts on first turn of key. With iridium plugs I had to repeatedly turn the key 5 to 11 times before the engine would start and run.
    Platinum plugs worked out better in this situation.
    Car is 2008 kia spectra, synthetic oil that’s changed every 5 to 6 thousand miles, coil paks replaced at 106k new, new plug wires at 106k. Car now diagnosed after install of platinum plugs and all stats are nearly within specs of a new engine.
    Apparently in some cases iridium plugs are not always better.

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