2025 Ram ProMaster Spark Plug Type & Gap

Quick reference

Why the right plug matters

Choosing the correct spark plug for your 2025 Ram ProMaster is more critical than you might think. Spark plugs are not a universal component; they are engineered with specific heat ranges and electrode materials to match the demands of your engine.

The heat range of a spark plug dictates how quickly it dissipates heat from its tip. A plug that's too hot can lead to pre-ignition and detonation, severely damaging your engine. Conversely, a plug that's too cold can foul prematurely with carbon deposits, leading to misfires and poor performance. The factory-specified plug ensures the optimal heat range for the 3.6L Pentastar V6, promoting efficient combustion and longevity.

Electrode material also plays a significant role in performance and durability. Modern vehicles like the ProMaster typically use:

• Iridium: This is the most common material for long-life spark plugs, offering exceptional durability and a very fine electrode tip for a strong, consistent spark. Iridium plugs are designed to last 100,000 miles or more, making them ideal for modern engines and extended service intervals.
• Platinum: Platinum plugs are also long-lasting, though typically not quite as durable as iridium. They offer good performance and are often found in engines that require extended service intervals but may not demand the absolute longest life.
• Copper: While copper is an excellent conductor of electricity, copper-core spark plugs have a much shorter lifespan due to softer electrode material. They are rarely specified for modern engines with coil-on-plug ignition systems and long service intervals due to their rapid wear.

The 2025 Ram ProMaster's 3.6L Pentastar V6 is designed for iridium spark plugs to achieve its impressive 100,000-mile service interval. Using a different material plug could lead to reduced performance and premature wear.

How to gap a spark plug

Properly gapping your spark plugs is crucial for optimal ignition and engine performance. While many iridium plugs come pre-gapped from the factory, it's always wise to double-check, especially if you're using an aftermarket plug. The specified gap for the 2025 Ram ProMaster's 3.6L Pentastar V6 is 0.043 inches (1.1 mm).

To gap a spark plug, you will need a spark plug gap tool. A wire-style feeler gauge is generally recommended for iridium and platinum plugs to avoid damaging the delicate electrode tip. Disc-style gap tools can sometimes scratch or damage the fine center electrode.

To gap your plug:

1. Insert the gauge: Carefully slide the appropriate wire gauge between the center and ground electrodes.
2. Check for resistance: You should feel a slight drag as the gauge passes through. If the gap is too small, gently bend the ground electrode outwards with the bending tool on the gauge until the correct gap is achieved. If the gap is too wide, gently tap the ground electrode on a clean, hard surface to close the gap slightly.
3. DO NOT bend the center electrode. This can permanently damage the plug.

Remember, even a slight difference in gap can affect combustion efficiency and lead to decreased fuel economy or misfires.

Replacement procedure tips

Replacing the spark plugs on your 2025 Ram ProMaster 3.6L Pentastar V6 is a manageable DIY task, but a few tips can make it smoother:

• Coil-on-plug removal: The 3.6L Pentastar V6 uses a coil-on-plug ignition system, meaning each spark plug has an individual ignition coil directly on top of it. To access the plugs, you'll need to carefully disconnect the electrical connector from each coil and then remove the coil hold-down bolt (if present). Gently twist and pull the coil straight up to remove it from the spark plug well. Avoid yanking on the electrical wires.
• Anti-seize debate: There's a common debate about using anti-seize compound on spark plug threads. For modern spark plugs with nickel-plated shells, manufacturers like NGK and Denso generally advise against it. The nickel plating acts as an anti-seize, and adding more can lead to over-torquing the plugs, potentially damaging the cylinder head threads or even the plug itself. If you do choose to use anti-seize (e.g., if you're working with older, non-nickel-plated plugs), be sure to reduce the torque specification by about 10-20% as lubricants reduce friction. For the ProMaster's factory-recommended plugs, it's best to install them dry at the specified torque.
• Dielectric grease on boots: Apply a small amount of dielectric grease inside the spark plug boot (the part that connects the coil to the plug). This helps to seal out moisture, prevents corrosion, and makes future removal easier.
• One at a time: Replace one spark plug at a time. This prevents you from accidentally dropping debris into an open cylinder and helps avoid mixing up coil packs or spark plug wires.
• Torque wrench is your friend: Always use a torque wrench to tighten the new spark plugs to the specified 13 lb-ft (18 Nm). Overtightening can strip cylinder head threads or crack the spark plug porcelain, while undertightening can lead to combustion gas leaks and electrode overheating.

Known issues

Fortunately, the 3.6L Pentastar V6 engine in the 2025 Ram ProMaster does not have any widespread