2018 Ram 1500 Spark Plug Type & Gap

Quick Reference

Why the right plug matters

Spark plugs are vital components in your engine's ignition system, responsible for igniting the air-fuel mixture in the combustion chamber. Using the correct spark plug for your 2018 Ram 1500 is crucial for optimal engine performance, fuel efficiency, and longevity. Three primary factors determine the right spark plug: heat range, electrode material, and gap.

Heat Range: This refers to the plug's ability to dissipate heat. A "hot" plug retains more heat, while a "cold" plug dissipates it faster. An incorrect heat range can lead to pre-ignition (too hot) or fouling (too cold), both of which can cause engine damage or reduced performance.

Electrode Material:

• Iridium: These are the most advanced and durable spark plugs, typically lasting up to 100,000 miles. Iridium is extremely hard and features a fine-wire center electrode, leading to a more focused and efficient spark. Both the 3.6L Pentastar V6 and 5.7L Hemi V8 in your 2018 Ram 1500 utilize iridium-tipped spark plugs from the factory.
• Platinum: Platinum plugs offer good durability, usually lasting around 60,000 miles. They are a step up from copper but not as long-lasting or efficient as iridium.
• Copper: These are the most basic and least durable, typically lasting 20,000-30,000 miles. They have good conductivity but wear quickly due to their softer material.

Gap: The gap is the distance between the center and ground electrodes. An incorrect gap can lead to misfires, reduced power, and poor fuel economy. Always set the gap to the manufacturer's specifications.

How to gap a spark plug

While many iridium spark plugs come "pre-gapped," it's always a good practice to verify the gap before installation, especially for the 5.7L Hemi, which still uses traditional plugs that may require gapping. Use a wire-type spark plug gapping tool, not a disc-style tool, as the latter can damage the fine iridium tip. Gently slide the gauge wire into the gap. If the gap is too small, you can slightly bend the ground electrode outwards with the tool. If it's too wide, carefully tap the ground electrode on a hard surface to close the gap. Exercise extreme caution to avoid damaging the delicate iridium tip.

Replacement procedure tips

Replacing spark plugs on your 2018 Ram 1500 can be a DIY task if you're comfortable with basic automotive work. Both the 3.6L Pentastar V6 and 5.7L Hemi V8 use a coil-on-plug (COP) ignition system.

1. Preparation: Always work on a cool engine. Disconnect the negative battery terminal for safety.
2. Access: On the 3.6L Pentastar V6, you'll need to remove the upper intake manifold to access the rear bank of spark plugs. This involves disconnecting various hoses, wiring, and the throttle body. The 5.7L Hemi is more straightforward, with all plugs easily accessible from above.
3. Coil-on-Plug Removal: Gently disconnect the electrical connector from each ignition coil. Then, unbolt the coil (if applicable) and twist and pull it upwards to remove it from the spark plug well. Be careful not to pull on the wires.
4. Spark Plug Removal: Use a spark plug socket with a rubber insert to remove the plugs. Turn counter-clockwise to loosen. Ensure the socket is fully seated to prevent stripping the plug.
5. Anti-Seize Debate: There's ongoing debate about using anti-seize on spark plug threads. For modern spark plugs with nickel-plated shells, anti-seize is generally not recommended by manufacturers like NGK, as it can alter torque readings and lead to over-tightening. If you choose to use it, apply a very thin amount to the threads only and reduce the torque specification by approximately 10-20%.
6. Dielectric Grease: Apply a small amount of dielectric grease inside the spark plug boot (the end that connects to the coil). This helps prevent moisture entry and makes future removal easier. Dielectric grease is an insulator and should not be applied to the electrodes themselves.
7. Installation: Hand-thread the new spark plugs into the cylinder head to prevent cross-threading. Once finger-tight, use a torque wrench to tighten them to the specified torque value. Reinstall the ignition coils, ensuring they seat properly, and reconnect electrical connectors. Reassemble any components removed for access.

Known issues

Fortunately, the 2018 Ram 1500 with either the 3.6L Pentastar V6 or 5.7L Hemi V8 does not suffer from any widespread or notorious spark plug issues like the earlier Ford 3-valve engine's breakage problem.

Need plugs replaced? Find a shop on Repairius.