Copper spark plugs -vs- others

tommudd

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Copper Spark Plugs vs. Iridium and Platinum: Understand for Top Performance​

January 27, 2012


Many people come to the point where they are forced to change the spark plugs on their vehicle and face a difficult decision; copper spark plugs or those of another type? You can find spark plugs in a variety of different metal combinations, including aluminum spark plugs, iridium plugs, platinum and more. Copper core spark plugs are still the most commonly seen, however, and many people agree that they are the best. However, the advertising that accompanies the different types of spark plugs is potentially misleading, so it's important to recognize the real difference between the spark plugs in question. In order to do that, it's necessary to first learn about what the metal in the spark plug is used for.

Purpose of the Metal

The metal in a spark plug serves a single basic purpose: to channel the electric energy from the plug wire through the spark plug so that it can be forced to the engine block in the form of a spark. Therefore, any metal that conducts electricity at all could potentially be used for a spark plug. The metal should also not get too hot; one of the main problems with some metals is that they overheat quickly, causing the electric charge itself to be compromised and the spark plug to not operate as smoothly.

Copper Spark Plugs

Copper spark plugs are generally considered to have the best performance of any spark plug type. This is potentially different from what advertising companies suggest, but the other metals are, unfortunately, not as conductive in general as copper is. Platinum and iridium plugs are more likely to overheat, which causes damage to the plug components and can compromise the delivery of the spark to the engine block.


Platinum and Iridium Plugs

Platinum and Iridium plugs perform at a lower level than copper spark plugs, because they are less conductive and they tend to overheat. However, the overall longevity of these two types of metal is better than copper plugs. In reality, copper has the best performance of all three and the worst longevity. Platinum has good longevity and the worst performance. Iridium has good longevity and a performance that is decent, which is why iridium plugs tend to be more expensive than any other type. Still, the difference between these plugs in terms of overall quality is minimal, as there is a trade off for each.
Most copper plugs need to be changed every 20,000 miles or so. Platinum and iridium plugs can often go for twice that before they require changing, but the overall performance will not be as good and you may have to deal with overheating of the plugs. This is potentially not worth the added cost of both platinum and iridium spark plugs, although the decision will depend upon your preference.
If you have any other questions about spark plugs and which are right for your vehicle, consult with a mechanic for more advice.
 

lfhoward

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I’ve been running the recommended NGK copper core plugs for the life of my Jeep, changing them every 30K miles per the maintenance schedule in the owners manual. I have never had any complaints about the performance, nor any misfires. The engine still has all 6 original ignition coils at 190,000 miles on the clock. I have heard the coils wear out sooner, eventually creating misfires if spark plugs with more electrical resistance (aka not copper) are used over long periods. Replacing coils is more expensive than replacing plugs by far.
 

kejobe

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In most applications, I agree. However, my Liberty when bought used had NGK Iriduim plugs in it. I changed them to NGK coppers and it was harder to start and ran/drove worse. I threw the Iridiums back in. Runs/drives just fine and without issue.

Also, when I had my 240SX I put NGK Iridiums in and it too ran smoother. This one actually got better MPG's also.

My Harley, hated the Iridiums, I run NGK coppers.

At least these are my experiences, others may very. I think it's a hit and miss. Engines can be temperamental, what mine likes, yours may not. And vice versa.
 

tommudd

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In most applications, I agree. However, my Liberty when bought used had NGK Iriduim plugs in it. I changed them to NGK coppers and it was harder to start and ran/drove worse. I threw the Iridiums back in. Runs/drives just fine and without issue.

Also, when I had my 240SX I put NGK Iridiums in and it too ran smoother. This one actually got better MPG's also.

My Harley, hated the Iridiums, I run NGK coppers.

At least these are my experiences, others may very. I think it's a hit and miss. Engines can be temperamental, what mine likes, yours may not. And vice versa.
And when I bought the 03 it missed/ rough idle and had plats in it
one of my bargaining points to get price down
brought it home , installed coppers ( NGK ) and took care of all issues
Also have found the same on 7 or 8 KJs had iridiums , rough idle etc , put correct plugs in and took care of all the customers complaints
 

Johnny O

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Copper Spark Plugs vs. Iridium and Platinum: Understand for Top Performance​

January 27, 2012


Many people come to the point where they are forced to change the spark plugs on their vehicle and face a difficult decision; copper spark plugs or those of another type? You can find spark plugs in a variety of different metal combinations, including aluminum spark plugs, iridium plugs, platinum and more. Copper core spark plugs are still the most commonly seen, however, and many people agree that they are the best. However, the advertising that accompanies the different types of spark plugs is potentially misleading, so it's important to recognize the real difference between the spark plugs in question. In order to do that, it's necessary to first learn about what the metal in the spark plug is used for.

Purpose of the Metal

The metal in a spark plug serves a single basic purpose: to channel the electric energy from the plug wire through the spark plug so that it can be forced to the engine block in the form of a spark. Therefore, any metal that conducts electricity at all could potentially be used for a spark plug. The metal should also not get too hot; one of the main problems with some metals is that they overheat quickly, causing the electric charge itself to be compromised and the spark plug to not operate as smoothly.

Copper Spark Plugs

Copper spark plugs are generally considered to have the best performance of any spark plug type. This is potentially different from what advertising companies suggest, but the other metals are, unfortunately, not as conductive in general as copper is. Platinum and iridium plugs are more likely to overheat, which causes damage to the plug components and can compromise the delivery of the spark to the engine block.


Platinum and Iridium Plugs

Platinum and Iridium plugs perform at a lower level than copper spark plugs, because they are less conductive and they tend to overheat. However, the overall longevity of these two types of metal is better than copper plugs. In reality, copper has the best performance of all three and the worst longevity. Platinum has good longevity and the worst performance. Iridium has good longevity and a performance that is decent, which is why iridium plugs tend to be more expensive than any other type. Still, the difference between these plugs in terms of overall quality is minimal, as there is a trade off for each.
Most copper plugs need to be changed every 20,000 miles or so. Platinum and iridium plugs can often go for twice that before they require changing, but the overall performance will not be as good and you may have to deal with overheating of the plugs. This is potentially not worth the added cost of both platinum and iridium spark plugs, although the decision will depend upon your preference.
If you have any other questions about spark plugs and which are right for your vehicle, consult with a mechanic for more advice.
I vote STICKY
 

WheelNut

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From an engineering/product planning perspective platinum et al plugs are spec'd from the factory on many vehicles now is the super long service life. If the plugs can survive the entire period the vehicle is under warranty then the manufacturer won't have to pay a technician to replace those plugs, which is much more expensive than the small BOM cost increase. Less servicing is better for things like consumer reports reliability ratings and other things that consumers look at when selecting their vehicle. For vehicles with aluminum heads platinum plugs have the added benefit of being less risky to change. Aluminum is much more susceptible to having a plug cross threaded, which is a very time consuming fix. If the plugs don't need to be changed there is no change of damaging those threads.

My KJ got new plugs recently and they were NGK coppers.
 

ltd02

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My wife's 2008 Sienna came with Iridium from the factory. We bought it new. Had them changed at about 120k. Now have 320k, so about 200k on the second set of iridiums. PITA to change but need to do it soon. Definitely wouldn't want to do that every 20-30k...

Checked the 3 plugs that are accessible and they look pretty good (somehow).

Ran the recommended in both my Liberties. I try to stick with what's spec'd.
 

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