Platinum v.s. Iridium



Why not tungsten?, it’s harder, has a higher melting point, and is way cheaper than iridium, which is one of the rarest metals on earth.


The problem with the 4 electrode version seems to occur on emissions testing. For some reason the single electrode version will sometimes pass the emissions test, while the 4 electrode version won’t. I don’t recall seeing a study on the topic, but apparently is common knowledge in the parts stores and emissions shops here in northern Calif.


Speaking of Iridium plugs, a friend mentioned a dealership mechanic telling him to not bother spending the money to change iridium plugs at the recommended 100,000 mile interval.

The mechanic told him the plugs will be fine at 100,000, and they see many going 200,000+ miles.

I can see the appeal to that logic, especially for the majority of car owners who don’t keep their vehicles that long.


You must know a lot of people with pretty old cars . . .

Because any OBD2 are model year 2000 and newer doesn’t get a dyno and tail pipe smog, only the plug-in test


I’m not sure how these “4-tipped plugs” made it that long to survive.

Back in 90-s at Europe, I used to have 1989 Opel and I bought into this “multi-tip hype”, so Bosch 4-tip plugs were installed and failed on me in under half a year - upon removal it was apparent they would not clean insulator area and ended up with heavy ash deposits there. The model installed was rated as “compatible” to my car, so it was not case of improper type.

Upon reinstalling some regular 1-tip plugs, that car gave me another few years of reliable service, no problems from the spark plugs side.

I’m really surprised Bosch still makes them and people still get sold on this.


I’m not sure if you’re aware of this . . . but some european cars actually left the factory with those plugs. I owned one such car in the past

And they worked fine for those applications. In fact, when it was time for new plugs, by mileage, I installed those, because that’s what was listed in the owner’s manual

But generally speaking, I wouldn’t install them on engines that didn’t specifically call for them in the owner’s manual


interesting… I was always under impression it is a kind of “snake oil”… apparently they had some legit uses


Years ago, I learned my lesson with multiple electrode plugs. I bought a set of Western Auto dual electrode spark plugs for my 1954 Buick. I had problems with the spark plugs fouling almost immediately. I had been able to go 25,000 miles on the AC 45 plugs that were specified in the owner’s manual. I found that Champion J8 plugs worked equally as well as the AC 45. I cleaned up the Western Auto plugs and tried them in the Lawn Boy mower. They didn’t even work there.
Stick with the plug the manufacturer’s recommended spark plugs.


Probably oxidizes. I’m sure somebody tested it.


It’s targeted or forum marketing. People are paid by companies to post positive reviews of their products to forums that are relevant to their product. This person has only ONE post. He joined on the day of the post. He posted to a thread that is years old, and only talked about how the sparkplug is so superior to everything else.

Trust me it’s spam.


It’s not pure Iridium, it’s a sintered alloy. I pointed out some of the benefits previously here- Iridium sparkplugs?

Here’s a good summary if interested-


A spark plug is just that, a spark plug. All the fancy (and expensive) ones do is provide better performance when under serious load conditions. Such as racing or pulling a load of some sort.
The Platinum and Iridium metals provide longer plug life. But you don’t need to go overboard. Use AC or Champion with the precious metal parts or just the standard type NGK plugs.
What’s the difference between a $5 Dollar Beer and a $10 Dollar Beer? Answer: $5

Happy motoring.


Frank, mcparadise has not been to this site since Nov, 2011.


No they don’t . In fact most (if not all race vehicles) don’t use Platinum or Iridium plugs. They need maximum performance, but not longevity. Platinum and Iridium plugs have inferior conductivity compared to standard plugs. Platinum or Iridium plugs offer longevity.


OK. Well the idea is still the same. I didn’t observe the timestamp.


@MikeInNH is right. Frankly, there’s no reason to use anything other than OEM spark plugs, and using different spark plugs often causes problems down the line…


And most OEM plugs these days are Platinum or Iridium. My Highlander and wife’s Lexus OEM plugs are Iridium. Not even sure if you can get a non-iridium plug. But I’d still use the Iridium plug even if standard Copper plugs were available because those back 3 plugs are a pain in the *ss to replace.


Yes I know my Focus uses Motorcraft Iridium. Not sure about our Honda Odyssey we just got a few weeks ago (haven’t finished the manual yet), but my guess is that they’re Iridium too. Hasn’t Iridium almost completely replaced Platinum since it lasts longer?


You make a good point. I suppose that all the Muliti-Electrode makers are relying on the motoring public to buy their wares.
However, Did anyone ever use Copper for an electrode?


From what I understand one reason for the precious metal plugs is b/c they’ll continue to work well for 100,000 miles without being replaced. That provides an emissions advantage, b/c the EPA knows a lot of owners don’t replace their spark plugs according to the manufacturer’s schedule. They replace them when the car won’t start. And it may have been running poorly for 6 months prior, producing higher than normal emissions the whole time. And there’s the “plugs are hard to access” advantage too.

But what if you are a person who always replaces the plugs on schedule, and own a car where plug replacement is a jiffy job, Corolla or Civic say. Would you still use a precious metal plug ?