2019 Chevrolet Silverado 3500HD Spark Plug Type & Gap

Quick reference

Why the right plug matters

Choosing the correct spark plug for your 2019 Chevrolet Silverado 3500HD is more critical than you might think. Spark plugs are not "one size fits all" components, and using the wrong type can lead to a host of problems, from reduced fuel economy and misfires to engine damage.

Heat Range

One of the most important specifications is the "heat range." This refers to the plug's ability to dissipate heat from the combustion chamber. A plug that's too "hot" (meaning it retains heat) can lead to pre-ignition and detonation, which can severely damage your engine. Conversely, a plug that's too "cold" (dissipates heat too quickly) can foul with carbon deposits, causing misfires and poor performance. The OEM-specified plugs are engineered to operate within the optimal temperature range for your Silverado's 6.0L V8 engine.

Electrode Metal: Iridium vs. Platinum vs. Copper

Modern vehicles like your 2019 Silverado 3500HD primarily use iridium spark plugs. Here's a breakdown of the common electrode materials:

• Iridium: This is the material of choice for your Silverado. Iridium is extremely hard and has a very high melting point, allowing for very fine electrodes. This fine tip concentrates the spark, improving ignition efficiency and extending the plug's lifespan significantly (often up to 100,000 miles or more). Your 6.0L V8 comes from the factory with iridium plugs.
• Platinum: Platinum plugs are a step up from copper, offering a longer lifespan due to platinum's higher melting point and resistance to wear. They typically last around 60,000-80,000 miles. While good, they generally don't match the longevity or performance of iridium.
• Copper: Traditional copper plugs have a large copper core for excellent conductivity, but their softer electrode material wears down more quickly. They are typically found in older vehicles or those with specific performance requirements that necessitate more frequent plug changes. They are not recommended for your Silverado.

Using the factory-specified iridium plugs ensures optimal performance and longevity for your 2019 Silverado 3500HD.

How to gap a spark plug

While many modern iridium spark plugs come "pre-gapped" from the factory, it's still critical to verify the gap before installation, as they can sometimes get bumped or bent during shipping. For your 2019 Silverado 3500HD 6.0L V8, the correct gap is 0.043 inches (1.1 mm).

1. Use the Right Tool: A wire-type spark plug gapping tool is generally recommended for iridium and platinum plugs. Avoid coin-style gapping tools, as they can damage the delicate fine-wire electrode.
2. Check the Gap: Carefully slide the correct wire gauge through the electrode gap. It should pass through with a slight drag.
3. Adjust (if necessary): If the gap is too small, use the adjustment tool on the gapper to gently pry open the ground electrode. If the gap is too large, gently tap the ground electrode on a clean, hard surface (like a wooden block) to close it. Never bend the center electrode, especially on iridium plugs, as it can easily break! Recheck the gap after each adjustment.

Replacement procedure tips

Replacing spark plugs on your 2019 Chevrolet Silverado 3500HD 6.0L V8 is a manageable DIY task, but a few tips can make the job smoother:

1. Work on a Cool Engine: Always perform spark plug replacement on a completely cool engine. This prevents potential damage to the cylinder head threads and reduces the risk of burns.
2. Coil-on-Plug Removal: Your Silverado uses a coil-on-plug (COP) ignition system. Each spark plug has its own ignition coil mounted directly on top. To access the plugs, you'll need to unclip the electrical connector from each coil and then remove the bolt (usually a 7mm or 10mm) securing the coil to the valve cover. Gently twist and pull the coil boot to remove it from the spark plug.
3. Anti-Seize Debate: The use of anti-seize on spark plug threads is a topic of debate. ACDelco and General Motors generally do not recommend using anti-seize on spark plugs with factory-applied coatings, which most modern plugs have. Applying anti-seize can alter the friction characteristics, leading to an over-torqued plug and potentially damaging the cylinder head threads. If you choose to use anti-seize on uncoated plugs, reduce the specified torque by about 10-20%.
4. Dielectric Grease on Boots: A small amount of dielectric grease applied to the inside of the spark plug boot (where it contacts the porcelain) can help prevent the boot from sticking to the plug and makes future removal easier. It also helps seal out moisture and prevent corrosion, improving electrical insulation.
5. Torque Wrench is Essential: Using a torque wrench is crucial to ensure spark plugs are tightened to the correct specification (11 lb-ft / 15 Nm). Over-tightening can damage the spark plug, strip the cylinder head threads, or crack the porcelain insulator. Under-tightening can cause the plug to loosen, leading to misfires or even ejection from the cylinder head.

Known issues

Fortunately, the 6.0L V8 (L96) engine in your 2019 Chevrolet Silverado 3500HD does not have widely documented common spark plug-related issues like the notorious two-piece spark plug breakage found in older Ford 3-valve engines or severe thread galling issues prevalent in some other designs.

However, general issues can arise if maintenance is neglected:

• Fouled Plugs: Running rich or having oil consumption can lead to carbon or oil fouling, causing misfires. Regular oil changes and addressing engine sensor issues can prevent this.
• Damaged Coils/Boots: Over time, the rubber boots on the coil packs can degrade, leading to arcing and misfires. Always inspect the coil boots when replacing plugs and replace them if they show signs of cracking or deterioration.
• Incorrect Gap: As mentioned, an incorrect gap (either from manufacturing error or improper adjustment) can lead to misfires, reduced fuel economy, and premature plug wear.

Sticking to the OEM-specified ACDelco 41-110 (or equivalent NGK/Denso) iridium plugs and following the recommended replacement interval will ensure reliable performance from your Silverado.

Need plugs replaced? Find a shop on Repairius.