Iridium vs Platinum Spark Plugs: What’s the Difference? 

On any gas-powered engines, spark plug replacement is part of the routine maintenance that needs to be performed. Copper spark plugs are far and away the most popular type available, but not all vehicles work well with them. Most newer vehicles use platinum or iridium spark plugs from the factory and nothing else will suffice.

At around $4 to $8 each for most vehicles, platinum spark plugs are only a small jump in price compared to copper. Iridium spark plugs cost approximately double, on average, with most options between $8 and $15 each. Aside from the price tag, how do you compare iridium vs platinum spark plugs, and which is best for your car?

Fortunately, you’ll always find the right option at AutoZone. Filter your search results using your year, make, model, and engine size and see compatible spark plugs at a price that works for you.

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Composition of a Spark Plug 

What’s meant by the different types of spark plugs? It helps to understand a spark plug’s construction.  

lawn mower or other non automotive spark plug product image
  • The insulator is a porcelain section that funnels the spark into the combustion chamber.  
  • The terminal allows the spark plug wire or ignition coil to fit snugly and securely onto the spark plug body. 
  • The housing is the metal body, typically made of steel, that’s threaded and is tightened into the cylinder head
  • The center electrode is a rod that reaches from the top terminal through to the bottom to conduct the electricity that creates the spark. It’s normally made of copper coated in nickel alloy. 
  • The spark jumps from the electrode center tip attached to the center electrode. This is where spark plug differences come from.  
  • The spark bridges to the curved ground electrode. While it’s made of steel, it can also be coated with a more conductive material.  

Essentially, the center electrode and ground electrode are where you’ll find the major differences between the types, like iridium and platinum plugs. 

Platinum Spark Plugs 

For a standard copper spark plug, the electrodes are often covered in nickel alloy for durability. However, platinum spark plugs are a major upgrade. Platinum is a much harder metal than the commonplace nickel alloy, which comes with a few benefits.  

  • Platinum holds its shape for much longer, so you can expect longer intervals between spark plug replacements. Most vehicles will last from 60,000 to 100,000 miles.  
  • The platinum tip has a higher melting point at around 3,215 F, meaning it erodes at a slower rate. 
  • They resist fouling. Since platinum burns hotter, it burns away deposits that would otherwise foul the spark plug. 

When you’re looking for platinum spark plugs, you may come across a couple of options. A single platinum plug will have a platinum center electrode with a nickel alloy ground. A double platinum spark plug also has a platinum spot on the ground electrode.  

Iridium Spark Plugs 

Another variety of spark plugs uses iridium instead of either nickel alloy or platinum. The center electrode is iridium for single iridium spark plugs while both the ground and center electrodes are coated for double iridium plugs. 

The benefits of iridium for a spark plug include:  

  • It’s as much as eight times stronger than platinum, so iridium can have a sharper center electrode that conducts a more durable, powerful spark. 
  • Iridium is much harder than even platinum, so it resists wear for up to 25% more lifespan. 
  • Iridium has a melting point over 4,400 F which ensures it can handle the hottest ignition systems.  

Iridium vs. Platinum: Which is Better? 

Which spark plugs are the best performing for your vehicle? The answer is… it depends. Platinum has properties that are better than copper spark plugs in many ways, and iridium spark plugs have benefits above those that platinum offers. But that doesn’t mean you can or should change the type of spark plug you use in your engine. 

When your vehicle is manufactured, the original spark plugs have been chosen by an engineer to make sure it runs smoothly, operates in the right temperature range, and will last between intervals. 

If your vehicle was built with copper spark plugs, there are typically options to upgrade to either platinum or iridium since they can outperform the originals. If your car has platinum plugs from factory, then it’s possible to upgrade to iridium, but you should never downgrade to copper. Likewise, iridium plugs from the factory should never be downgraded to platinum or copper, or you could risk both performance and longevity issues. 

To find the right spark plug for your vehicle, search AutoZone options using your vehicle information. Or, if you prefer, ask an associate for help. You’ll always find the right parts for the job, and at a great price. If the job is too big for you, seek out one of our Preferred Shops to help you do the job.

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FAQ/People Also Ask 

Do iridium spark plugs make a difference? 

Iridium is harder than both platinum and copper, and it can last much longer comparatively. As well, your car might not run properly if it’s intended to use iridium spark plugs and they’ve been downgraded.

Why are platinum spark plugs better? 

Platinum has a higher melting point and is denser than copper, making it an excellent choice for long-lasting replacements.

What spark plugs are better than iridium?  

Iridium spark plugs are at the high end of the scale. However, a double iridium electrode offers excellent durability.

Do iridium spark plugs increase horsepower? 

It’s a fallacy that iridium spark plugs increase horsepower. Rather, they can ensure that the air-fuel misture is burning consistently, harnessing your engine’s power efficiently.

What’s the best spark plug for performance? 

Generally, iridium spark plugs are considered the best option for high-performance engines since they tolerate high temperatures best and have an extremely reliable spark.

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