2023 Chevrolet Suburban Spark Plug Type, Gap & Torque Specs

As an ASE-certified master technician, I regularly field questions from customers about the maintenance schedule for modern GM SUVs. The 2023 Chevrolet Suburban is a powerhouse, offering two robust gasoline V8 engines (the 5.3L L84 and 6.2L L87) alongside the 3.0L Duramax diesel. (Note: The Duramax uses glow plugs, not spark plugs, so this guide focuses exclusively on the gas V8s).

Replacing spark plugs in a modern GM V8 is standard maintenance, but adhering to the correct part numbers, gaps, and torque specs is critical to keeping that engine running smoothly and avoiding misfires.

Quick reference

Why the right plug matters

Modern engines are incredibly sensitive to spark plug specifications. Using the correct plug ensures the proper heat range, which is how efficiently the plug pulls heat away from the combustion chamber. If a plug is too hot, it can cause pre-ignition and engine knock; too cold, and it will foul with carbon deposits.

The electrode metal is equally important. The 2023 Suburban comes from the factory with iridium spark plugs. Iridium is six times harder and eight times stronger than platinum, and far superior to traditional copper. This advanced metallurgy allows for a finer electrode tip (providing a more concentrated spark) and ensures the plugs can easily survive the GM-mandated 97,500-mile replacement interval without degrading. Never downgrade to copper or standard platinum plugs in these engines, as they will burn out rapidly.

How to gap a spark plug

Even though most premium iridium plugs (like the ACDelco 41-114) come pre-gapped from the factory, an ASE-certified tech will always verify the gap before installation. Shipping and handling can cause the ground strap to get bumped, closing the gap.

1. Use the right gauge tool: For iridium plugs, never use a traditional coin-style ramp gauge. The ramp can easily snap the fragile iridium center electrode. Instead, use a wire-type feeler gauge.
2. Measure gently: Slide the 0.040 in (1.01 mm) wire between the center electrode and the ground strap. It should pass through with a slight "drag."
3. Adjusting the gap: If the gap is too tight, use the bending tool on your gauge to carefully apply a light bend to the ground strap. Never pry against the center electrode.

Replacement procedure tips

Working on the 5.3L and 6.2L V8s in the 2023 Suburban is relatively straightforward, but there are a few modern best practices to follow:

• Coil-on-Plug Removal: These engines use a coil-near-plug or coil-on-plug ignition system. Before removing the coils and wires, use compressed air to blow out the spark plug wells. You do not want dirt or grit falling into the cylinders when you extract the old plugs.
• The Anti-Seize Debate: Modern ACDelco and NGK plugs feature a special zinc-chromate or nickel-plated coating on the threads designed to prevent seizing in the aluminum cylinder heads. GM strictly advises against using anti-seize compound. Anti-seize acts as a lubricant, which can easily cause you to over-torque the plug, leading to stripped threads or a broken plug shell. Install them dry.
• Dielectric Grease: Always apply a small dab of dielectric grease to the inside of the spark plug boot before reattaching it. This prevents voltage leaks, keeps moisture out, and guarantees you’ll be able to get the boot off easily at the next service interval.

Known issues

While the 2023 Suburban V8 engines are generally reliable, it's worth understanding the context of spark plug failures in the industry:

• Cracked Porcelain / Broken Shells: You might have heard horror stories about broken spark plugs (most notoriously the 2-piece plugs in older Ford 3-valve 5.4L engines). Fortunately, GM’s Gen V V8 engines do not suffer from this design flaw. However, cracking the porcelain on a Suburban plug is still possible if your socket isn't perfectly straight during installation. Always use a proper spark plug socket with a rubber insert and avoid applying lateral pressure.
• Ionization Sensing and Misfires: Modern GM ignition coils often use ionization sensing to detect misfires and engine knock. If you use cheap, non-OEM plugs, the altered electrical resistance can confuse the Engine Control Module (ECM), resulting in phantom misfire codes, rough idling, or reduced fuel economy. Stick to ACDelco or equivalent premium NGK/Denso iridium plugs.

Need plugs replaced? Find a shop on Repairius.