Replaced Iridium with Platinum Plugs

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Robenstein

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The parts store computers all over said my car takes Platinum plugs from the factory. I took the factory ones out and they were iridium. Didnt look too bad, but I replaced them anyways.

I noticed the car started better, but I just wanted to get an opinion here.

Any negatives of doing this?

Car is a 2006 Scion TC with the 2.4 Yota motor.
 
I wouldn't see why. My car takes platinum from factory, but I put iridium plugs in mine and it runs great. Platinum plugs supposedly last longer than iridium, that is the main difference.
BTW, I'm in Ames too, glad the snow is finally gone!
 
Originally Posted By: Ashtray77
I wouldn't see why. My car takes platinum from factory, but I put iridium plugs in mine and it runs great. Platinum plugs supposedly last longer than iridium, that is the main difference.
BTW, I'm in Ames too, glad the snow is finally gone!

Actually, its the opposite, iridium is supposed to last longer than platinum.
 
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Spark is spark. You're getting longer life with the Platinum and Iridium plugs with Iridium being the latest and longest lasting. You didn't do any harm going "down" to a Platinum plug but if you went to a copper than that would cut your service intervals.
 
No, you won't have a problem.

But yes, the 2az-fe is OEM iridium.

The iridium plugs you replaced aren't fine wire performance plugs, they're likely more similar to whatever platinums you bought. The advantage is a 100,000 mile + service life.
 
I thought Platinum Plugs were 100,000 Mile plugs. I just replaced some in my Taurus, it had gone 98,000 before it started missing on the 3rd cylinder. I didn't know if it was wires , the solenoid pack, or the plugs. So I just did a tuneup, NGK platinum tipped went in there.

From what I understood the Iridium are supposed to be Lifetime plugs.
I've never used the Iridium plugs, but have thought about going to them as there are a few plugs on my Xterra that are darn near impossible to get to.

Has anyone ever worn out an Iridium plug? I thought they were supposed to last close to forever.
 
The ACDelco platinum go 100,000 no problem. Why would anyone need a spark plug to last any longer than that. I don't have a clue what more the advantage of Iridium is. Spark plugs can have so many fancy gimmicks and claims the are dangerously close to the "oil additive" debate. Like this;
 
http://en.wikipedia.org/wiki/List_of_elements_by_melting_point

The melting point of iridium is higher than for platinum.

I expect that other factors, such as resistance to corrosion at high temperatures comes into play. Otherwise tungsten would have seemed to be a top choice.

http://en.wikipedia.org/wiki/Iridium

As to why you would like to have your plugs last longer than 100,000 miles, some cars have plugs that are very difficult to change. A plug that reliably lasted 200,000 miles would seem to be worth a premium.

http://www.densoiridium.com/faq.php has some claims, but I don't know that that page is entirely accurate. For example, I find the statement that "Fifty million years ago, an asteroid composed almost entirely of the precious metal Iridium (Ir-77) struck the earth, creating the Gulf of Mexico" to be highly suspect.
 
The plug itself may "last" 100,000 miles but its service life is less than optimum before that. As another poster has mentioned, the plugs were removed 98,000 miles because of misfire issues.

The electrodes wear out and the spark isn't the same spark as it once was. So, a spark isn't a spark really that is why split fires and +4s exist. They dont' "last" any longer but they are supposed to provide an optimum spark for a longer duration.
 
Originally Posted By: pcfxer
The plug itself may "last" 100,000 miles but its service life is less than optimum before that. As another poster has mentioned, the plugs were removed 98,000 miles because of misfire issues.

The electrodes wear out and the spark isn't the same spark as it once was. So, a spark isn't a spark really that is why split fires and +4s exist. They dont' "last" any longer but they are supposed to provide an optimum spark for a longer duration.
Like this.
splitcom.html
 
Subaru uses an Iridium plug made just for the EJ255(they went to Denso to design it) and in the Forester at least specs a 60k mile change interval.

Coopers are changed every 15k or sooner in the motor if you prefer them(some do).

I guess being turbocharged puts more stress on the plugs.
 
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Best to have the iridum electrode WITH a Platinum enhancement on the ground tab.
MANY vehicles use a "wasted spark" system that has a positive spark on 1 bank and a negative spark on the other bank.
What this means for spark plug life is that on one side of the motor, the electrode wears faster.....and on the other side of the motor, the ground tab actually wears faster.

Using a multi-pronged spark plug does NOT seem to help, at least not on FORD.

My '96 FORD Windstar specifies "double Platinum" spark plugs, which has platinim on the electrode AND on the ground tab.
The Factory original spark plugs, also rated for 100K miles had a platinum electrode and no platinum enhancement on the ground tab on 1 side of the motor.......and the spark plugs on the other side had the platinum enhancement on the ground tab.
However, these are not available in the aftermarket (it is confusing enough already), so that is why you need the double platinum.

Also note that not all Iridium are long life spark plugs.......Denso sells a "Power Plus" Iridium spark plug that has a 4mm electrode.......and they (Denso) rates them for ONLY 30K miles.
Their Long Life spark plug for the same application has a 7mm electrode and platinum enhancement on the ground tab and rates them "up to" 120K miles.
So, it pays to read up on what you are thinking of buying.
 
Iridium have a higher melting point as was mentioned, but platinum has a little better oxidation resistance. I think they mix some small amount of alloy with iridium for oxidation performance.

Anyway there are long life platinums and iridiums that have a thicker tab, and then there are plugs with a thinner electrode tab. Usually the iridium have ones available with a thinner electrode for whatever performance advantage that gives. Those are not longer life than some platinums. I think the bottom line is NGK laser iridiums are longlife and the best, but long life platinum probably have about the same service life ~100K miles, and both deterioate some eventually.
 
Yes I agree. Your best bet other than OEM is to get NGK laser platinums or laser iridiums, because they are OE long-life style with platinum on the ground electrode depending as required. Denso doesn't seem to have as good long-life OE style coverage.
 
Originally Posted By: willix
The ACDelco platinum go 100,000 no problem. Why would anyone need a spark plug to last any longer than that. I don't have a clue what more the advantage of Iridium is. Spark plugs can have so many fancy gimmicks and claims the are dangerously close to the "oil additive" debate. Like this;




AC Delcos going 100k is not the norm. I can't tell you how many I've changed out before 80k. I just changed the one's on my 06 GMC with 51k miles and they were Iridium but had a miss. Changed a friends CTS plugs out at 74k miles. Maybe it depends on the use and I'd prefer to say long life plugs can go "up to" 100k miles.
 
The point is they don't required service according to the schedule for 100,000 miles. They often last that long. That would be fact. I never owned a car for more than 70,000. Every car I have ever owned has had the plugs replaced as good measure as part of a initial maintenance that one would do to a used car.
 
Denso iridium was designed to go 200k and they have data which shows that they will last that long without a material loss of performance. If you are interested, give me your email and I will send you the research report.
 
http://en.wikipedia.org/wiki/List_of_elements_by_melting_point

The melting point of iridium is higher than for platinum.

I expect that other factors, such as resistance to corrosion at high temperatures comes into play. Otherwise tungsten would have seemed to be a top choice.

http://en.wikipedia.org/wiki/Iridium

As to why you would like to have your plugs last longer than 100,000 miles, some cars have plugs that are very difficult to change. A plug that reliably lasted 200,000 miles would seem to be worth a premium.

http://www.densoiridium.com/faq.php has some claims, but I don't know that that page is entirely accurate. For example, I find the statement that "Fifty million years ago, an asteroid composed almost entirely of the precious metal Iridium (Ir-77) struck the earth, creating the Gulf of Mexico" to be highly suspect.
 
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