7 Best Spark Plugs for 4.0 Jeep Reviews 2020

Of all the vital cogs that keep your Jeep Cherokee XJ 4.0 performing superlatively, the spark plug is undoubtedly one of them. The Jeep Cherokee is the ultimate in comfort, style, and sports utility, having bagged more awards than any other SUV in its lifetime. If you continue to drive your 4.0 Jeep using a rusted and worn-out spark plug, the chances are that your SUV will underperform.

Therefore it is essential to change the stock or OEM spark plug of your Jeep Cherokee if you've driven the vehicle for over 30,000 miles. Replacing the depleted spark plug with a brand new best spark plugs for 4.0 Jeep will ensure that your SUV stays in top form. A brand new heavy-duty spark plug is designed meticulously, making it capable of tolerating intense heat and pressure that builds up within the cylinders.

Additionally, the best spark plugs for Jeep 4.0 are innovatively designed, which prevents fuel additives dregs from accumulating on the caps.      

_Our Selections of 5 Best Spark Plugs for 4.0 Jeep 2020 Compared!_

Why do you need a suitable spark plug for your 4.0 Jeep?

Even though your Jeep 4.0 comes outfitted with a hardwearing spark plug, you should have the electrical device inspected by a mechanic after driving for about 30,000 miles. Maintenance of your Jeep Cherokee's spark plug is crucial if you want to make the most of your SUV. The best spark plug for 4.0 Jeep performs two basic functions-igniting or sparking the mixture of air and fuel, and removing heat from the combustion chamber.

Spark plugs serve as efficient heat exchangers as they suck superfluous thermal heat energy from the combustion compartment to transfer heat to the engine's cooling system. As the factory-fitted spark plug in the Jeep 4.0 becomes older, its ability to create an electrical spark for igniting the air/fuel blend decreases. The electrode and ignition coil of a spark plug suffers wear and tear in due course.

You'll need to replace the old and worn-out spark plug with a new one if you want the Jeep 4.0's engine to run smoothly. Ensure you follow the instructions mentioned in your vehicle's manual when opting for a spark plug replacement. For example, if your SUV came with a platinum spark plug, then ensure that the new device is of the same type.

Different types of spark plugs

Spark plugs which help mix compressed hot air and fuel to start combustion, are available in four distinct varieties. You'll come across spark plugs whose core is made from copper, iridium, platinum, and double platinum. The range you'll choose invariably depends upon the design of your vehicle's engine and the spark plug type outfitted by the manufacturer.

  • Platinum spark plugs

Owing to platinum being harder than copper, spark plug electrodes crafted from the former tend to be more durable than copper electrodes. Also, platinum's hardness enables the metal to resist high engine temperatures better, eventually allowing it to check fouling and accumulation of sediments. Platinum spark plugs are ideal for vehicles that are relatively new and feature an electronic ignition system.

  • Copper spark plugs

Copper spark plugs come with a solid core of copper and a thick coating of a nickel alloy. Copper spark plugs are more suitable for older vehicles featuring low-voltage ignition system and have a shorter lifespan than iridium or platinum plugs. Some heavy-duty vehicles indispensably need copper spark plugs owing to the metal's excellent electrical conductivity.

  • Iridium spark plugs

Iridium spark plugs are designed almost in the same way as platinum plugs but tend to be more hardwearing and long-lasting. Spark plugs made of iridium are also more efficient than platinum plugs as the former requires less voltage for creating sparks. Hence iridium plugs command a higher price in comparison to their platinum counterparts in the automotive market.

  • Double iridium spark plugs

Double iridium spark plugs have two layers of the metal, like spark plugs featuring two platinum discs. Spark plugs with dual layers of iridium are capable of delivering the firepower even under extreme conditions.

  • Double platinum spark plugs

Double platinum spark plugs, as the name indicates, have two discs or layers of the metal for allowing rearward leaping sparks. Since dual platinum spark plugs enable sparks to jump both in front and backward directions, they do not erode rapidly.

Best Spark Plugs for Jeep 4.0

Top 7 Picks of The Best Spark Plugs for 4.0 Jeep

Spark plugs as we know are an important part of the engine that ensures you drive peacefully. They are available in different quality standards and at different price levels. Hence, selecting the perfect option could be confusing. With the detailed reviews for the best selling spark plugs for your 4.0 Jeeo we have tried to help you buy the perfect option based on your needs.

#1) NGK V-Power Spark Plugs for Jeep Engine Kit Set Tune Up- One of Best Spark Plugs for Jeep TJ

The 6-Piece NGK V-Power Spark Plugs work flawlessly with older models of cars, jeeps, and SUVs that come preassembled with nickel-plated spark plugs.

 This innovative and versatile spark plug from NGK features a V-styled channel nickel alloy electrode, which positions the electrical device close to the air/fuel mixture. Owing to the spark plug tip closer positioning or placement to the blend of air and fuel, the ignition is created faster.

This NGK spark plug tends to be more efficient and performance-oriented in comparison to the conventional or standardized nickel-type spark plugs.

The V-Power spark plug for 1997-2006 Jeep TJ 4.0L L6 not only offers better ignitability than standardized nickel-electroplated spark plugs but also consumes less electrical power for creating sparks. These sports utility vehicle and OE-certified spark plugs feature an aluminum silicate ceramic insulator for facilitating enhanced heat transfer.  

Key Features

  • V-style grooves on a nickel-electroplated electrode
  • Spark plug tip positioned closer to air/fuel mixture
  • Aluminum silicate ceramic insulator
  • Pure copper core of spark plug promotes effective heat transfer
  • Distinctive five-rib insulator checks flashover or short-circuiting  of sparks  


  • Spark plugs come with cold-rolled threads for thwarting trivalent metal plating and cylinder head damage
  • These spark plugs check corrosion and seizing of the engine cylinders
  • Every spark plug is designed like an insulator and features anti-corrosion electroplating for guaranteeing smooth installation and detachment
  • Solid copper core for facilitating better heat conductivity and diffusion resulting in reduced emissions and enhanced fuel emissions   


  • Many customers have complained that the spark plugs get overheated fairly quickly

#2) Autolite XP985-4PK Iridium XP Spark Plug- Another Best Jeep Spark Plugs

The Autolite XP985-4K Iridium XP Spark Plug is perfectly companionable with almost all models of the Jeep Cherokee XJ launched in the US from 1983 to 2001 and worldwide from 2014.

The Autolite XP985-4K Iridium spark plugs make the most of the state-of-the-art automotive technology for keeping your Jeep 4.0's engine in good humor.

These Autolite spark plugs feature an iridium-reinforced 0.6mm wire design along with premium platinum side wires for promoting quicker ignition. The signature and patented platinum side wire technology also help boost engine performance.

Key Features

  • Brand new design featuring copper and platinum core
  • Electroplated with nickel
  • Innovative prominent 'Autolite' symbol; the outdated metal-style branding has been done away with
  • Terminal nut attached to the gasket
  • No rib grooves
  • Enhanced side wire alloy    


  • Enhancement of side wire alloy for boosting durability and resilience
  • Motor seat gasket attached to terminal nut for improving overall performance
  • There's no chance of erosion or corrosion as rib stripes have been done away with
  • OE-approved design guarantees that the spark plug is compatible with your vehicle
  • Iridium-reinforced platinum alloy 0.6mm super fine wire center electrode for creating sparks quickly


  • The spark plugs could be difficult to gap without touching the iridium tip

#3) Sixity Auto V-Power Spark Plugs for Jeep Grand Cherokee 4.0L L6

This 6-Pcs NGK V-Power Spark Plugs are thoroughly companionable with 1999-2004 Jeep Grand Cherokee4.0L and older automobiles featuring nickel-tipped spark plugs.

The NGK V-Power Spark Plug works with Jeep Grand Cherokee (1999-2004) 4.0L L6 models as well as old vehicles outfitted with nickel alloy spark plugs.

This set of six spark plugs comes with a V-shaped groove nickel alloy center electrode, thereby positioning the plug nearer to the air/fuel mixture. This closer placement helps in speeding up the process of creating sparks for igniting the air-fuel mixture.

Key Features

  • Resistor-style spark plug
  • V-groove center electrode
  • Cold-rolled threads
  • Small electrode gap suitable for light-duty vehicles
  • Trivalent metal plating


  • OE-certified spark plug with an alumina silicate ceramic insulator for efficient heat transfer
  • Thick copper core furnishes enhanced heat dispersion and electrical conductivity resulting in lower emissions and better fuel economy
  • Exclusive five-rib insulator checks spark flashover
  • Triple gasket sealing for doing away with leakage of gas beyond the carapace


  • Copper spark plugs tend to have a short life span

#4) NGK (3459) ZFR5N V-Power Spark Plug Pack

The NGK (3459) ZFR5N works with a wide range of Jeep Grand Cherokee 4.0L models as the electrical device has been built to OEM requirements.

The NGK (3459) ZFR5N V-Power Spark Plug has been designed with meticulous care to ensure quicker ignitability even under poor burn conditions. 

The superior design of this NGK V-Power spark plug boosts ignitability, improves heat transfer, and ultimately enhances engine performance. Every component of the spark plug starting from the ground electrode to the resistor has been shaped out of premium materials. No wonder this spark plug tends to be highly resistant to abrasion and corrosion. 

Key Features 

  • Designed according to OEM specifications
  • Resistant to corrosion and chemical erosion
  • Reduces emissions
  • Betters fuel economy


  • Painstakingly designed for faster combustibility under poor burn conditions
  • Innovative design for better engine performance and efficient heat transfer
  • Trivalent metal plating contributes towards boosting the functional life of the plug


  • Susceptible to attracting sediments of fuel's additives

#5) Champion RC12LYC (412) Copper Plus Replacement Spark Plug

The RC12LYC (412) Copper Plus Replacement Spark Plug from Champion serves as an ideal replacement for your 1997 Jeep Grand Cherokee 4.0L.

This Champion RC12LYC (412) comes equipped with a solid copper core electrode, which furnishes better conductivity and heat dissipation for boosted performance. On the other hand, the proprietary Ultraseal™ coated encasing makes the spark plug extremely resistant to corrosion and erosion.

All these features coordinate together to enable the spark plug to attain optimal temperatures rapidly. Additionally, the performance-driven spark plug can hold on to a steady operating temperature irrespective of the engine's load capacity. 

Key Features

  • Proprietary SAC-8 semiconductor resistor
  • Patented Ultraseal™ layered shell for optimum corrosion resistance
  • Center electrode features a solid core of copper
  • Applications: Marine, small engines, and automotive
  • Performance guaranteed: Designed keeping SAE and ISO standards in mind


  • Very reliable and durable: Designed as per SAE and ISO standards
  • Proprietary Ultraseal layered shell for optimum corrosion resistance
  • Copper core center electrode for promoting precise control of temperature range


  • These copper spark plugs are not compatible with electronic distributor-based ignition systems

#6) NGK V-Power Spark Plug ZFR5N (6 Pack) for Jeep Grand Cherokee 1994-2004

The V-Power Spark Plug ZFR5N featuring NGK's proprietary V-Groove technology works with Jeep Grand Cherokee models from 1994 through 2004 4.0L.

NGK's V-Power Spark Plugs reinforced with the manufacturer's signature V-Groove technology enhances your Jeep Grand Cherokee's engine performance.

This spark plugs from NGK boost up engine performance and fuel mileage by reducing the ignition system's voltage requirements and improving ignitability.

At the same time, the spark plugs have robust anti-fouling properties that also contribute toward boosting engine performance and bettering fuel mileage.

You can bet that these NGK V-Power spark plugs will last almost a lifetime owing to their high resistivity to chemical and electrical wear and tear. The sparks or ignitions take place towards the rim of the center electrode, thereby preventing heat absorption by the electrode, thanks to the V-Groove technology. The V-Groove technology enables the core of the flame to intensify effectively and rapidly, resulting in thorough burn and enhanced performance.

Key Features

  • Solid copper core of spark plug electrode
  • Projected type insulator
  • Thread dimension of spark plug: 14mm
  • Gasket-style spark plug seat
  • Spark plug reach: 0.750 inches


  • Immaculate replacement for Jeep Grand Cherokee 1999-2004 4.0L/242
  • Has the approval of OEM (original equipment manufacturer): perfectly safe to use
  • Extremely resistant to chemical and electrical erosion
  • Ensures reduced fuel emissions and better fuel economy
  •  Trivalent metal plating with superlative anti-seizing and anti-corrosion features


  • Wear and tear could happen faster, the manufacturer's claims notwithstanding

#7) Jeep Wrangler Grand Cherokee 4.0L Spark Plugs Mopar OEM

The Jeep Wrangler Grand Cherokee (set of six) Spark Plugs serve as the perfect replacement for Jeep Cherokee 4.0L engine 2000-2001, Jeep Grand Cherokee 1999-2006 Jeep Wrangler, and Jeep Cherokee 1999-2003

The Jeep Wrangler Grand Cherokee 4.0L Spark Plugs by Mopar are compatible with the Jeep above Grand Cherokee models. These OEM-certified spark plugs efficiently deliver electric current from your SUV's ignition system to the combustion chamber for igniting the compressed air/fuel mixture.

The nickel-plated spark plug, together with the attached terminal nut and gasket help boost engine performance, reduce toxic emissions and improve fuel economy.

Key Features

  • Nickel-plated spark plug
  • High-quality ceramic insulator
  • Terminal nut and gasket joined together
  • Designed with meticulous care for durability


  • Compatible with Jeep Cherokee (2000-2001), Jeep Grand Cherokee (1999-2003), and Jeep Wrangler (1999-2006) models
  • Sturdy Built Quality offering strong durability
  • Reduces Toxic Emissions
  • Improves Fuel Economy


  • Most SUV owners have reported that these spark plugs are of inferior quality
Spark Plugs for 4.0 Jeep

Aspects to Consider Before Buying the Best Spark Plug for 4.0 Jeep

The engine under the hood of your Jeep 4.0L is distinctive and, therefore, different from the drivers of all other SUVs makes. So it follows that the Jeep Grand Cherokee's 4.0L engine will be compatible with only one type of spark plug. Instead of banking on the mechanic's recommendations, follow the advice of the vehicle manufacturer when it comes to replacing the old spark plug.

Keep the following considerations in mind when shopping for a new spark plug for your Jeep Grand Cherokee 4.0L:-

  • Spark plug Type

We have covered the types of spark plugs available in the market in the previous section.

  • Electrode Gap

A spark plug's electrode gap influences the magnitude or intensity of the spark, which in turn determines the combustion level of the air-fuel mixture. The electrode gap of a spark plug is specified in millimeters, and engine performance depends considerably on the electrode gap specification.

Spark plugs having a wider electrode gap provide a cleaner burn or combustion but may not fire on every cycle. On the other hand, plugs with a small or narrow electrode gap do not offer a clean burn but tend to fire on nearly every period.

  • Heat Rating

A spark plug's heat rating is defined as the range of temperatures in which the plug will function smoothly. You get spark plugs with a high heat rating or low heat rating, and a number indicates the score. Sparks plug carrying the number of a higher value will work better under colder temperatures.

Low-heat rated spark plugs are known as hot-type plugs that are suitable for LCVs and light-duty vehicles. The firing end of such spark plugs becomes hot quickly as well as offers a larger surface area to hot gases. Spark plugs with a high-heat rating variously referred to as cold-type plugs have firing ends that take time to heat up.

Owing to this unique feature of cold-type spark plugs, they're better suited for heavy-duty and high-performance vehicles.


  • What are the qualities of an efficient spark plug?

The best spark plug for 4.0 Jeep-like any other quality spark plug performs the primary function of igniting the gasoline to initiate combustion. Additionally, an efficient spark plug can go a long way in boosting the SUV's performance and reduce toxic emissions, eventually helping bring down maintenance costs. Moreover, a quality spark plug can boost your vehicle's horsepower, thereby enabling you to drive smoothly on elevated terrains.

  • What types of spark plugs are compatible with Jeep Grand Cherokee 4.0L?

Both the 4.7L V-8 and 4.0L six cylinder engines of Jeeps come outfitted with copper core resistor-type spark plugs.

  • What are the benefits you enjoy when you replace the old spark plug?
  • Lower toxic emissions
  • Smooth engine start
  • Improved fuel economy
  • Complete combustibility of air/fuel mixture
  • What to keep in mind while replacing the spark plug of your Jeep 4.0L?

Always heed by your vehicle manufacturer's instructions outlined in the owner's manual. By rule of thumb, always stick to the type of spark plug that was initially installed in your Jeep 4.0L.


In this review of the seven best spark plugs for 4.0 jeep, we analyzed four products of NGK and one product, each of Mopar, Champion, and Autolite. We came to the conclusion copper spark plugs are more suitable for older models of Jeep Grand Cherokee 4.0L, while platinum and iridium spark plugs are ideal for newer Jeep 4.0L models.

Take a look to our reviews for best oil for jeep 4.0, Best Exhaust for 3.5 Ecoboost f150 and Best Air Filter for your 7.3 Powerstroke

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