Reviews of the Best Spark Plugs 2017: Including High Performance Spark Plugs

We’ve carefully selected some of the best spark plugs on the market and narrowed down our list into two categories, iridium spark plugs and platinum spark plugs. These two types really provide the best starting power and more consistent sparking. Because each vehicle can use a different size spark plugs, we focused a lot on brand and not so much on the plug size. When checking price, make sure you locate the correct size spark plug for your vehicle.

Top Rated Iridium Spark Plugs - Quick Reference Chart

Best
NGK Spark Plug - Iridium, Laser (4477) ITR6F13
Better
Denso Spark Plug - Iridium Power, (4477) ITR6F13
Good
Bosch Spark Plug - Iridium, Fine Wire (9601) HR9KII33Y Original Equipment
AC Delco Spark Plug - Iridium, 41-121 Professional
Autolite Spark Plug - Iridium, XP5224

Top Rated Platinum & Double Platinum Spark Plugs - Quick Reference Chart

Best
NGK Spark Plug - Platinum, Laser (6737) PZFR5Q-11
Better
Denso Spark Plug - Platinum TT, (4504) PK20TT
Good
Bosch Spark Plug - Double Platinum, Fine Wire (8121) VR8SPP33X Original Equipment
Autolite Spark Plug - Double Platinum, APP104
AC Delco Spark Plug - Platinum, 41-948 Professional

Best Platinum and Double Platinum Spark Plugs

NGK Spark Plug - Platinum, Laser (6737) PZFR5Q-11


This NGK spark plug has a laser welded platinum tip providing a consistent spark. They come “pre-gapped” meaning you should only need to remove the old plugs and screw these in, no extra steps necessary. They are setup to resist abrasion and corrosion. Finally, it allows for smoother idling.

Denso Spark Plug - Platinum TT, (4504) PK20TT


Denso makes some superior spark plugs and that’s what you will get with our pick here. The first feature that makes these so great is the price. You will be hard-pressed to find another platinum spark plug that has similar quality and the price. They even beat some copper core plugs in price. This spark plug has platinum on both the ground electrodes and the center core. Users rated this Denso spark plug with some of the highest reviews we could find.

Bosch Spark Plug - Double Platinum, Fine Wire (8121) VR8SPP33X Original Equipment


These Bosch spark plugs are designed to original equipment specifications. They are double platinum, with platinum on the center and ground electrodes. Users report these as a perfect fit and were very happy with them. You will get the Bosch name to back up this quality product. These are some world class spark plugs for the price.

Autolite Spark Plug - Double Platinum, APP104


Autolite manufactures some fantastic spark plugs. When it comes to the platinum and double platinum categories, Autolite spark plugs are awesome. These plugs are engineered for a longer life and work to optimize the performance of your engine. Autolite double platinum spark plugs have full platinum tips and platinum on the side and center electrodes. These are some of the best double platinum spark plugs we could find.

AC Delco Spark Plug - Platinum, 41-948 Professional


These AC Delco spark plugs round out the list of the platinum and double platinum category. They are manufactured as a single piece with three glass types ensuring a gas tight seal. Although they have a 100% copper core, like most platinum/double platinum spark plugs, the tips are coated in platinum. They are designed to regulate the energy from the spark plug in order to seal against compression pressures.

Best Iridium Spark Plugs

NGK Spark Plug - Iridium, Laser (4477) ITR6F13


Iridium spark plugs from NGK are a high quality work of art. These spark plugs are engineered with a laser welded iridium center electrode tip. They also feature a welded platinum disc on the back of the ground electrode to help extend the life. This spark plug boasts faster starts and quicker acceleration. Customers who purchased would tend to agree. This iridium plug might be one of the highest rated spark plugs we’ve reviewed.

Denso Spark Plug - Iridium Power, (4477) ITR6F13


According to the manufacturer, the Denso spark plug with iridium center electrode has the smallest diameter at . 4 mm. This smaller electrode promises that it will maximize firing potential. Denso has a patented 360 degree laser welding process that ensures structural strength and exceptional quality. This plug has a fantastic price point that will allow just about anyone to replace all the plugs in their car with world class spark plugs.

Bosch Spark Plug - Iridium, Fine Wire (9601) HR9KII33Y Original Equipment


Bosch spark plugs have a factory pre-set gap that ensures installation will be a breeze. The iridium center electrode is a .6 mm ultra fine wire. This means the ignitability will be exceptional. These plugs even had an exceptional user comment section. Customers didn't have a single negative thing to say about them. One thing to mention with these plugs, and all spark plugs for that matter, is make sure you check the gap. Your vehicle’s engine will have a specific setting to make the engine run optimally and if the gap is too big or too small, it could potentially do more harm than good. Especially over the long run.

Autolite Spark Plug - Iridium, XP5224


The iridium Autolite spark plugs will give you the best bang for your buck among the iridium level. The come with a special patented technology that will resist wear known as V-trimmed platinum sidewire. Users were very positive with regard to this plug. Some reported an increase in power while some said there was a noticeable improvement with the starting of their vehicle. The Autolite iridium spark plugs rank in right around the platinum price point. When it comes to value, you won't go wrong with Autolite and we are confident that these are some of the nicest spark plugs available.

AC Delco Spark Plug - Iridium, 41-121 Professional


AC Delco spark plugs with iridium provides your vehicle with the smooth performance and improved engine idle. These spark plugs are an exact match to the OEM plug, according to users. AC Delco iridium plugs even help to burn away carbon deposits as they form meaning that they will actually work proactively to increase fuel economy. They are even improved to help with cold weather starting. They are reasonably priced for iridium spark plugs and you won't be disappointed with them.

How we chose our spark plugs

When selecting spark plugs to review, we looked carefully at the four types of spark plugs. We thought about the pros and cons of each type and finally settled on the spark plugs that offer the most bang for the buck. We found that the ideal spark plugs to offer this are the platinum, double platinum and iridium. Not because they are the most expensive, but because they will perform the best and last the longest.

Copper core are going to cost a bit less, but will need to be replaced twice as often, resulting in you paying more over the long run. As with all equipment you purchase for your car, make sure you check your vehicle’s manual or a parts catalog to verify the parts will fit.

A Brief History

Spark plugs are a vital component to an internal combustion engine. Over the last 150 or so years, they have been refined and undergone transformation into what we know today as the modern spark plug.

Étienne Lenoir is credited as using the first electric spark plug in his gas engine in 1860. Since then, many others have contributed and put forth their versions of the spark plugs. It wasn’t until around the 1900s that the first commercially viable spark plug became available. Fast forward to today, where we have multiple types of spark plugs and many manufacturers producing spark plugs. With all the different types, and all the different brands, how will you know which one is truly the best?

That’s where we come in. We are here to provide some insight into the different types, as well as select the best spark plug so you don't have to try and guess for yourself.

Standard Spark Plugs & High Performance Spark Plugs

As we mentioned before, it is important to understand the differences in spark plug types so you will be able to make the best decision for you and your vehicle. All major spark plug brands are manufactured into four possible types. Their rating, life and cost typically increase the further down the list you go. Here are the four main central electrode styles.

Copper Core Spark Plugs are typically going to be cheap spark plugs when it comes to cost, but they still have value. These spark plugs are meant to be changed often and are a great alternative to the more expensive spark plug styles. Copper core is generally known as “standard” or “normal” spark plugs. The reason these need to be changed frequently is that copper, like other metals, will erode over time (just much quicker). Copper just so happens to be a fantastic conductor, and therein lies the value. You can expect copper core spark plugs to last anywhere from 20,000 to 40,000 miles.

The Best Spark Plugs

Changing your spark plugs is easy and can be done at home.

Platinum Spark Plugs are typically more expensive than copper core, and thus last a little longer. The reason platinum spark plugs are more expensive is fairly obvious -- platinum is a more rare and precious metal than copper. One fantastic benefit to platinum over copper is that platinum will not erode nearly as fast as copper. So while platinum spark plugs may be more expensive than their copper core friends, you won't need to change them as often. Platinum style are some of the greatest spark plugs because they will last typically two times as long as copper. Some car manufacturers even suggest that these only need to be changed after 100,000 miles.

Double Platinum Spark Plugs simply include more platinum within the spark plug itself and not solely on the tip. The platinum on other parts of the spark plug will help it operate. The platinum can be found on places such as the ground electrodes. Because there is more platinum, expect to pay a little more for these spark plugs.

Iridium Spark Plugs are generally considered top of the line, or high performance spark plugs. They are very comparable to platinum and double platinum spark plugs. The thing that sets these apart is that the core is made of a “fine wire” offering better conductivity. This means that more power will reach the tip and it will almost always produce a spark, even when these things get dirty. Their lifespan is close to that of platinum. Iridium often makes the best spark plug.

When to change a spark plug?

After reading our reviews of the best spark plugs, you may be thinking to yourself: “I’ve never changed my spark plugs and I’ve driven a long way. How do I know if I have a bad spark plug and need to change it?”

​You could use any number of ways to tell if you need to replace a bad spark plug. One way is by comparing your odometer and your last spark plug change. If you’ve driven over 100,000 miles since you last checked or changed your spark plugs, it’s most likely time now. Alternatively if you've driven over 40,000 miles, you could reference your vehicle’s owner's manual and see if you have standard copper core spark plugs. If you do, you definitely want to consider replacing them.

​Another way to tell if you've got bad spark plugs is by listening to, or feeling the response of your car.

  • Do you have trouble starting it?
  • Does it have a rough idle?
  • Are you noticing higher fuel consumption as time goes on?

Reference this article to see if you have any of these issues. Again, if you do, you should consider purchasing some new spark plugs.

Finally, you can tell if you need to replace a bad spark plug by pulling them out and having a look. They should appear slightly blackened from normal firing in the combustion chamber. If they appear rusty, bent, corroded or other abnormal colors, you probably want to replace them. The image above shows a used spark plug compared to a new one. The spark plug on the left has normal wear without any major signs of engine issues. 

Should I replace my spark plugs, or just clean them?

Something that you must consider when looking at your spark plugs is whether they need replacing or if a simple cleaning will suffice. A lot of fuel stabilizers, octane boosters and fuel injector cleaners will be an all-in-one treatment and preventative for your engine. Using one of these products can clean and prevent buildup on your spark plugs as well as performing their main duty. Most of these products can be used immediately after changing your spark plugs to prolong their life.


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