Iridium Spark Plugs

[bobbob]

They are standard equipment in my Toyota. The guy at Auto Zone
tells me they are $15 apiece NGK's and will last 100K. I think
they're pricey. Are they that good? Thanks

 

[MC5W20]

I don't know. I bought a Champion set for 5.49 each. Plus I get a $2.50 each rebate, that makes them $3 each. I haven't put them in yet so I don't know if they are for real.

I have seen the NGK for like $10 each.

 

[Silk]

Come to New Zealand and buy them for $35 each.

 

[JOD]

There are 2 types of "Iridium" plugs. Some use Iridium on the firing electrode only(NGK IX), some use it on the ground and firing electrode both (NGK Laser). The double Iridium are obviously more expensive.

If you have a car in which it's difficult to access the plugs, the longer life of the double Iridium plugs is definitely worth it. That say within their spec'd gap much longer than a conventional plug. I pulled mine @ around 80K, and they'd have gone another 20K.

If I had a car with easy access, I'd probably use a cheaper plug and change it more often.

 

[mechtech2]

Consider double platinum plugs.
Iridium is super duper, but plats are excellent.

 

[Silk]

Iridium are usually cheaper than platinum.Double plat or iridium are used for replacement plugs in waste spark engines....or else you use a centre plat electrode for one side of the coil,and an earth plat plug for the other side.

 

[hounddog]

How many miles on the plugs your replacing? I'm going to use them in my 09 Hemi so I don't have to change plugs out at 30,000

 

[Merkava_4]

Originally Posted By: mechtech2
Consider double platinum plugs.
Iridium is super duper, but plats are excellent.


Funny you should mention that: My Buick came from the factory with double platinum plugs installed and I have about 103,000 miles on them now. I'm getting ready to replace them before wintertime sets in. Upon doing the ACDelco part number search, I've learned that they no longer offer double platinum plugs for the 3.8L V6 -- just the iridium.

 

[sprintman]

The best by far. Pity they don't go in my BMW but we have then in our Outback (about to be sold), and will in our Pajero/Montero we get this week if they have plugs available. Worth every cent

 

[SteveSRT8]

standard in many new cars.

Platinum/iridium hybrids are excellent as well.

A great upgrade for the Hemi owner who is tired of changing plugs all the time.

 

[cryption]

Yes, NGK is that good.

 

[willix]

If that Toyota had Iridium plugs OEM you should replace them with Iridium. Premature coil failure may result from using other types of plugs.

 

[SuperDave456]

Platinum are supposed to last 100K miles. I started having a misfire on my Taurus after about 90,000 miles with the Motorcraft platinum plugs. Figured I would go ahead and change them out along with wires and solenoid pack.

I replaced them with NGK platinum's with both the platinum electrode and ground having the platinum pickup. They were 3-4 bucks each at Auto Zone.

The Iridium, with iridium on both ground and electrode, are supposed to last at LEAST 100K miles from what I have read. People change them out early for piece of mind, but I've never heard of one going "bad".

Anyone out there with Iridium plugs that have lasted 150-200k miles?

 

[Audi Junkie]

Here's my oem Honda after 50k

I regapped and re-installed them.

 

[Vikas]

Iridium Laser is actually cheaper than Platinum Laser and is supposed to last longer.

 

[mechtech2]

Audi - I see precious metal tips on the center electrodes of only two plugs. [It could be the picture, though]
If this is so, I hope you put the plugs back exactly where they came out of!
Most replacement plugs are double tipped to avoid waste spark ignition problems.

 

[severach]

Many Toyota V6 require the top of the engine to be removed to replace the rear spark plugs. Bad spark plugs ruin the expensive coils. Double Iridium go in there no matter what the cost.

 

[zmelli]

Originally Posted By: JOD
There are 2 types of "Iridium" plugs. Some use Iridium on the firing electrode only(NGK IX), some use it on the ground and firing electrode both (NGK Laser). The double Iridium are obviously more expensive.

If you have a car in which it's difficult to access the plugs, the longer life of the double Iridium plugs is definitely worth it. That say within their spec'd gap much longer than a conventional plug. I pulled mine @ around 80K, and they'd have gone another 20K.

If I had a car with easy access, I'd probably use a cheaper plug and change it more often.


Unable to find the "Iridium" plugs with Iridium on both the electrode and ground? Denso states Iridium electrode and Platium ground Ref P/N 3377 and P/N 3297.

 

[zmelli]

Originally Posted By: zmelli
Originally Posted By: JOD
There are 2 types of "Iridium" plugs. Some use Iridium on the firing electrode only(NGK IX), some use it on the ground and firing electrode both (NGK Laser). The double Iridium are obviously more expensive.

If you have a car in which it's difficult to access the plugs, the longer life of the double Iridium plugs is definitely worth it. That say within their spec'd gap much longer than a conventional plug. I pulled mine @ around 80K, and they'd have gone another 20K.

If I had a car with easy access, I'd probably use a cheaper plug and change it more often.

Unable to find the "Iridium" plugs with Iridium on both the electrode and ground? Denso states Iridium electrode and Platium ground Ref P/N 3377 and P/N 3297.

Construction of NGK and Denso plugs is similar for the most part, the big difference being Denso's use of a 0.4mm Iridium tipped centre electrode - claimed to be the world's smallest production centre electrode, where NGK's IX centre electrode is 0.6mm. As with NGK Iridium, and indeed most other spark plugs, the narrower the centre electrode is, the lower the potential difference (voltage) that is required to jump the gap between centre and ground electrodes. It follows that the Denso plug will require an even lower 'spark jump' voltage than the NGK plug. The Denso plug also utilises a 'u-grooved' ground electrode which is claimed to aid in the production of a 'flame core' which further improves the combustion process. In theory, all the benefits offered by NGK Iridium plugs are further improved by the Denso Iridium plugs - with the exception of service life. The smaller diameter of the Denso centre electrode means that less wear can take place before the plugs' optimum service life is exceeded.

Denso also manufacture long life Iridium power plugs such as SVK20RZ8, VK22PR-Z11 etc. These maintain the 0.4mm Iridium centre electrode but also have a platinum 'chip' in the ground electrode to allow performance to be maintained for a much longer service life (up to 60000 miles). These plug types are usually recommended for high power turbo charged engines where wear may otherwise be accelerated.

 

[zmelli]

Iridium use represents the most significant technological advance in automotive spark plug manufacturing, since platinum was introduced in the early eighties. As vehicle manufacturers produce increasingly complex and efficient automobiles, there is a greater need for long-life plugs that can tolerate leaner fuel mixtures and improved combustion processes. DENSO has responded to this need by developing its Iridium alloy, originally for OE applications. For example, many newer Lexus’ and Toyota models carry an ultra long-life Iridium plug variation (.7mm with platinum tipped ground) that is capable of up to 120,000 miles of service. DENSO Iridium Power plugs, with their .4mm center electrode, have been developed for performance applications. Because gradual wear will “round-off” firing points over time, the concentrated firing power and voltage requirement benefits will be reduced. For this reason, DENSO advises replacement after 30,000 miles.