Best Spark Plugs For Infiniti M35 – 7 Options Reviewed

I recently spent a weekend diving deep into the VQ engine bay of my M35. Getting to those rear plugs is always a chore, so when I replace them, I want assurance they’ll last. Finding the right set is crucial for maximizing performance and fuel economy. Below, I’ve compiled a practical guide reviewing the best spark plugs for infiniti m35, focusing on reliable options that deliver a smooth idle and consistent power delivery for both early and late model years.

IMAGE	PRODUCT NAME	AMAZON LINK
	1406 Double Iridium Spark Plug for Infiniti EX35 FX35 G25…	View on Amazon
	Set of 6 Ignition Coil Pack & Iridium Spark Plugs…	View on Amazon
	UF550 Ignition Coil Pack & Spark Plugs Compatible with…	View on Amazon
	AULINK UF550 C1670 Ignition Coil Spark Plug 6 PCS For…	View on Amazon
	UF550 Ignition Coil & 1406 Double Iridium Spark Plug for…	View on Amazon
	UF401 Ignition Coil Pack and Iridium Spark Plugs Set of…	View on Amazon
	Set of 6 Ignition Coil Pack and Spark Plugs fits…	View on Amazon

1406 Double Iridium Spark Plug for Infiniti EX35 FX35 G25 G35 JX35 M35 M35h M56 Q50 Q70 QX60/Nissan Altima Maxima Murano Quest 350Z V6 Replaces # DILKAR7B11 (Set of 6)

This set is an excellent choice if you know your ignition coils are still in great shape and you only need fresh spark plugs. Designed specifically as a direct replacement for the popular OE DILKAR7B11 plug (used in later VQ models, including 2009-2010 M35), these double iridium plugs are built for maximum longevity, capable of running up to 100,000 kilometers reliably. You’ll notice an immediate improvement in cold-start performance and throttle response once installed.

Key features that stand out:

• Double Iridium Construction: Offers superior wear resistance and extended service life.
• Consistent Spark: Engineered to provide stable, consistent ignition for better combustion.
• OE# 1406 Replacement: A direct cross-reference for the factory-installed plugs.

Pros:
– Extremely long working life (up to 100,000 km)
– Designed to improve cold starting and overall smoothness
– Affordable OE-equivalent replacement

Cons:
– Does not include ignition coils, requiring separate purchase if needed.

Best for: 2009-2010 M35 owners looking for high-mileage, plug-only replacements.

Expert Opinion: This plug design is standard for the later VQ M35 engines. The double iridium tip ensures durability, making it ideal for the rear cylinders where maintenance access is difficult and longevity is paramount.

Set of 6 Ignition Coil Pack & Iridium Spark Plugs Compatible with 2007-2020 Nissan Altima Maxima Murano Pathfinder Quest 350Z Infiniti Q50 Q70 QX60 EX35 FX35 G25 G35 JX35 M35 M35h V6 3.5 Replace UF550

If your M35 (2009-2010) is experiencing misfires or hesitations, often the coils are to blame alongside old plugs. This comprehensive kit provides both the UF550 ignition coil packs and matching iridium spark plugs, offering a complete ignition system refresh. This bundle restores acceleration and fuel economy by ensuring powerful, stable spark delivery. It’s an efficient way to address multiple potential issues at once.

Key features that stand out:

• Full Ignition System Refresh: Includes 6 coils (UF550) and 6 iridium plugs.
• Stable High Energy Output: Coils are engineered for powerful and consistent spark delivery.
• Improved Performance: Designed to restore acceleration and enhance fuel economy.

Pros:
– Excellent value proposition by bundling coils and plugs
– Direct replacement for the later VQ 3.5L engine
– High-quality iridium plugs included

Cons:
– Aftermarket coils may not offer the same longevity as high-end OEM components.

Best for: Owners performing a 90k+ mile ignition overhaul on their later model M35 (2009-2010).

Expert Opinion: When replacing spark plugs on high-mileage M35s, replacing the coils simultaneously is highly recommended, especially given the labor involved. The UF550 standard ensures compatibility for the specified years.

UF550 Ignition Coil Pack & Spark Plugs Compatible with INFINITI EX35 FX35 G25 G35 JX35 M35 M35h Q50 Q70 QX60 Nissan Maxima Murano Altima Pathfinder Quest 2.5L 3.5L 2008 2009 2010 2011 2012 2013 6Pcs

This kit is another robust option for refreshing the ignition system of your M35 (2009-2010). It emphasizes superior performance through high-quality materials like durable copper windings and ceramic insulation in the coils. By delivering a stable, high-voltage output, it ensures consistent spark plug ignition, which directly translates to improved fuel combustion and efficiency, helping your V6 engine run smoothly and powerfully.

Key features that stand out:

• Superior Performance: Enhances ignition efficiency and engine power output.
• High-Quality Materials: Uses durable copper windings and a robust ceramic insulator in the coils.
• Wide Compatibility: Covers a vast range of VQ 3.5L engines using the UF550 coil.

Pros:
– Strong focus on durable, high-temperature resistant coil construction
– Aids in improving fuel combustion and engine response
– Comprehensive 6-piece kit

Cons:
– Requires verification against the specific M35 model year, as VQ engines changed coil types.

Best for: Drivers prioritizing coil pack material quality alongside new iridium spark plugs.

Expert Opinion: The focus on copper windings and ceramic insulation in the coil is a good indicator of heat resistance, which is vital in a performance V6 engine bay. This kit aims for reliability under stress.

AULINK UF550 C1670 Ignition Coil Spark Plug 6 PCS For Infiniti EX35 FX35 G25 G35 JX35 M35 M35h Q50 Q70 QX60,Nissan 350Z Maxima Quest Pathfinder Murano Altima Xterra 3.5L V6

AULINK provides a dependable aftermarket solution for the late-model M35, offering both the UF550 coils and trivalent metal plated spark plugs. A key strength of this option is the strict quality control, manufactured in TS16949 certified facilities, ensuring that the components meet global industry standards for performance and leakage testing. They even back the product with a 1-year or 50,000 km warranty for peace of mind.

Key features that stand out:

• TS16949 Certified: Indicates manufacturing adherence to strict automotive quality standards.
• Trivalent Metal Plating: Used on the spark plugs for superior corrosion resistance.
• Direct OEM Replacement: Matches numerous OE and cross-reference part numbers (UF550, C1670).

Pros:
– Manufacturer warranty provides confidence in longevity
– Rigorous testing and certification process
– Complete set covering all cylinders

Cons:
– Warranty mileage might be slightly lower than expected for some competitors.

Best for: Value-conscious buyers who still demand rigorous quality control testing.

Expert Opinion: The inclusion of certified quality checks and a warranty is a significant bonus when purchasing aftermarket ignition components. This product offers a reliable blend of affordability and confirmed quality standards.

UF550 Ignition Coil & 1406 Double Iridium Spark Plug for Nissan Altima Maxima Murano Pathfinder Quest 350Z/Infiniti EX35 FX35 G25 G35 JX35 M35 M35h Q50 Q70 QX60 3.5L V6 C1670 22448-JA10C 5C1727

This is essentially the bundled version of Product 1, combining the robust 1406 double iridium spark plugs with UF550 coils designed for superior longevity. If your M35 has over 100,000 miles, this kit addresses the wear and tear on both components simultaneously. The coils are designed with internal ferrite noise suppressors to prevent radio frequency interference, ensuring clean signals and consistent engine operation.

Key features that stand out:

• Double Iridium Spark Plug: Guarantees a long service interval of 100,000 kilometers.
• Noise Suppressor Coils: Prevents RF interference for cleaner electrical performance.
• Complete Replacement: Addresses engine misfire, rough idle, and poor fuel economy simultaneously.

Pros:
– Ideal for maximizing engine smoothness and fuel efficiency
– Combines high-longevity plugs with tested coils
– Coils designed to resist heat fractures

Cons:
– High performance comes with a slightly higher price tag than basic bundles.

Best for: M35 owners (2009-2010) prioritizing the longest possible lifespan and reliability for their new plugs and coils.

Expert Opinion: The use of double iridium combined with anti-interference coils makes this kit a top-tier choice for those who rarely want to deal with the spark plug replacement job again for a long time.

UF401 Ignition Coil Pack and Iridium Spark Plugs Set of 6 Compatible with Infiniti FX35 G35 M35 Nissan 350Z 2003 2004 2005 2006 2007 2008 3.5 V6,Replace# C689, 5C1430, 5027

Crucially, this kit targets the earlier generation of the Infiniti M35 (specifically 2006-2008 models). These models use a different coil pack (UF401) than the later M35s. This set provides high-purity copper windings in the coils and advanced iridium spark plugs, which optimize MPG and reduce carbon deposition. It also features high alumina ceramic insulation in the plugs for excellent heat resistance.

Key features that stand out:

• UF401 Compatibility: Specifically for 2006-2008 M35/G35/FX35 models.
• Optimized MPG: Designed to improve engine fuel efficiency by 15-20%.
• Laser-Welded Iridium Electrode: Ensures a concentrated and strong spark for precise ignition.

Pros:
– Perfect fitment for early M35 owners (critical distinction)
– High-quality German-imported coil materials
– Extended plug life of up to 100,000 miles

Cons:
– Compatibility is limited to the earlier model years of the M35.

Best for: Owners of the 2006, 2007, or 2008 Infiniti M35 needing a full ignition system refresh.

Expert Opinion: For older VQ engines, getting the correct UF401 coils is non-negotiable. This bundle ensures the necessary fitment while offering robust material quality to handle higher operating temperatures.

Set of 6 Ignition Coil Pack and Spark Plugs fits for Infiniti FX35 G35 M35 Nissan 350Z 2003 2004 2005 2006 2007 2008 3.5 V6 Replaces# UF401 4469

Similar to the previous entry, this kit provides a complete six-piece ignition overhaul for the 2006-2008 M35, utilizing the UF401 coils. It focuses on enhanced performance, claiming to deliver 15% more energy than OE coils. Built to achieve or exceed OE specifications, this set promises an immediate upgrade in engine performance, reducing hesitation and ensuring improved cold-weather starts. It also comes with a generous 24-month warranty.

Key features that stand out:

• UF401 Specific Fitment: Ensures proper installation for earlier M35 models.
• Enhanced Power Output: Claims to upgrade energy by 15% compared to stock coils.
• 24-Month Warranty: Provides confidence and long-term support for the purchase.

Pros:
– Strong focus on upgrading power output over factory specs
– Reliable direct OEM design for easy installation
– Longest warranty period reviewed in the UF401 category

Cons:
– Specific plug type (4469) might not offer the ultra-long life of double iridium plugs.

Best for: Owners of older M35 models seeking a performance boost alongside restored reliability.

Expert Opinion: Claiming a 15% energy upgrade is appealing for those driving older VQ motors. This is a solid, warrantied choice for the early M35 that needs restored punch and reliability.

Comparison Short Insights

Choosing the right components among the best spark plugs for infiniti m35 hinges heavily on your model year and overall engine health.

First and foremost, you must know your M35 year: 2006–2008 M35s require the UF401 coil kits (Products 6 & 7), while 2009–2010 M35s use the UF550 coil kits (Products 2, 3, 4, 5). Mixing these up will result in incompatibility.

For the later M35 (UF550 generation), if your engine is running rough or experiencing misfires, a full kit is the way to go. Kits like Product 5 offer the best blend of coil quality and plug longevity due to the double iridium plugs and noise-suppressing coils. However, if your coils are relatively new, Product 1 is the most cost-effective solution for long-term plug replacement.

For older M35 models (UF401 generation), the choice is between reliability and potential slight performance gains. Product 6 emphasizes high-purity copper windings and long plug life, making it a stable choice, while Product 7 highlights a performance upgrade backed by a longer warranty.

Final Verdict

Making the switch to new spark plugs is essential maintenance, and getting the best spark plugs for infiniti m35 is simplified by understanding your specific needs:

The Best “Plug Only” Upgrade (2009-2010 M35):
If you simply need replacement spark plugs and your coils are in excellent shape, the 1406 Double Iridium Spark Plug Set (Product 1) offers fantastic OE matching quality and maximum service life, meaning you won’t have to tackle the job again soon.

The Best Value Ignition Refresh (2009-2010 M35):
For owners needing a full system overhaul without breaking the bank, the Set of 6 Ignition Coil Pack & Iridium Spark Plugs (Product 2) provides a reliable, comprehensive replacement of both major ignition components.

The Definitive Choice for Older M35 (2006-2008):
Owners of the earlier M35 must opt for a UF401 kit. The UF401 Ignition Coil Pack and Iridium Spark Plugs Set (Product 6) stands out for its high-quality construction materials and focused fitment for the prior VQ generation.

Best Spark Plugs For Infiniti M35 FAQ

What are the main symptoms that indicate I need new spark plugs in my M35?

The most common symptoms include engine misfires (especially under acceleration), a rough or vibrating idle, difficulty starting the engine (particularly in cold weather), a noticeable decrease in fuel efficiency, and a general loss of power or hesitation when accelerating. If you experience these issues, it’s a strong signal your spark plugs (and potentially ignition coils) need replacement.

How often should I replace the spark plugs in my Infiniti M35?

For most M35 models using Iridium or Double Iridium plugs (like the factory DILKAR7B11 plugs), the standard recommended replacement interval is between 90,000 to 105,000 miles. If you are using lower-grade Platinum or Copper plugs (though not recommended for the M35’s VQ engine), that interval would drop significantly to 30,000–50,000 miles.

Is it necessary to replace the ignition coils when replacing the best spark plugs for infiniti m35?

While not always strictly necessary, it is highly recommended, especially on M35s over 100,000 miles. Since the rear spark plugs are notoriously difficult to access on the VQ35DE/HR engine, replacing the ignition coils (which are usually the UF401 or UF550 type) simultaneously prevents you from having to repeat the labor-intensive process soon after if a coil eventually fails. Bundled coil/plug kits offer the best value for this comprehensive maintenance.

What is the difference between the UF401 and UF550 ignition coils for the M35?

The difference relates to the specific generation of the VQ engine used in the M35. The UF401 coil pack is generally found on earlier VQ35DE engines (2006-2008 M35), while the UF550 coil pack is used on later revisions (2009-2010 M35). Always verify the correct coil type based on your specific model year and VIN to ensure proper fitment.

Do I need to gap the new Iridium spark plugs before installing them in my M35?

Iridium spark plugs are precision-engineered and typically come pre-gapped from the factory specifically for your vehicle. It is generally advised not to adjust the gap on fine-wire iridium plugs, as it can easily damage the delicate iridium tip. Always check the required gap for your specific M35 model (usually around 0.044 inches) and confirm the plug matches, but avoid forcing adjustments.

Will replacing my old spark plugs improve my M35’s fuel economy?

Yes, absolutely. Worn or fouled spark plugs lead to inefficient combustion, causing the engine control unit (ECU) to compensate by slightly increasing fuel delivery or causing misfires. Replacing them with quality double iridium options ensures a strong, consistent spark, maximizing combustion efficiency and typically leading to a noticeable improvement in overall fuel efficiency.