2015 Ram 1500 Spark Plug Type & Gap

Quick reference

Why the right plug matters

Choosing the correct spark plugs for your 2015 Ram 1500 is crucial for optimal engine performance, fuel economy, and longevity. The spark plug's primary function is to ignite the air-fuel mixture in the combustion chamber. If the plug isn't right, you can experience misfires, reduced power, and even engine damage.

Heat Range: Spark plugs are designed with a specific heat range, which refers to their ability to dissipate heat. A "hot" plug retains more heat, while a "cold" plug dissipates it faster. Using 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 cause carbon fouling, leading to misfires and poor performance. Your Ram 1500's engine is engineered for a specific heat range, and using the OEM-recommended plug or an equivalent aftermarket option ensures proper heat management.

Electrode Metal: The material of the spark plug electrode significantly impacts its lifespan and performance.

• Copper: These are the most basic and least expensive plugs. Copper is an excellent conductor, but it wears down relatively quickly. They are often found in older vehicles or those with less demanding ignition systems. The 5.7L HEMI V8 often comes with copper plugs from the factory, hence the shorter replacement interval.
• Platinum: Platinum plugs offer better durability and longevity than copper. They have a finer electrode, which provides a more consistent spark. Single platinum plugs typically feature a platinum-tipped center electrode, while double platinum plugs also have a platinum pad on the ground electrode, further extending their life.
• Iridium: Iridium is the hardest and most durable of these metals, allowing for the finest wire electrodes. This results in a highly focused and efficient spark, promoting better combustion and fuel efficiency. Iridium plugs last the longest and are often the preferred upgrade for vehicles that originally came with copper or platinum, like the 3.6L Pentastar V6, which often uses iridium from the factory, or as an upgrade for the 5.7L HEMI.

How to gap a spark plug

While many modern iridium and platinum spark plugs come pre-gapped, it's always a good practice to double-check the gap before installation. An incorrect gap can lead to misfires and poor fuel economy.

1. Obtain a gap tool: You'll need a round wire-style gap tool for accurate measurement. Coin-style gap tools can damage the fine electrodes of iridium or platinum plugs.
2. Measure the gap: Carefully slide the appropriate wire gauge from your tool between the center and ground electrodes. It should slide with a slight drag.
3. Adjust if necessary: If the gap is too small, gently bend the ground electrode away from the center electrode using the bending tool on your gap gauge. If the gap is too large, carefully tap the ground electrode on a hard, non-abrasive surface to close the gap. Be extremely gentle, especially with iridium plugs, as their fine electrodes are fragile.
4. Re-check: Always re-measure the gap after any adjustment to ensure it's correct.

Replacement procedure tips

Both the 3.6L Pentastar V6 and the 5.7L HEMI V8 in your 2015 Ram 1500 utilize a coil-on-plug (COP) ignition system, meaning each spark plug has its own individual ignition coil directly mounted on top of it. This eliminates the need for spark plug wires.

1. Coil-on-plug removal: Carefully disconnect the electrical connector from each ignition coil. Then, gently twist and pull upwards on the coil to remove it. Some coils may require a specific tool or a bit more force to dislodge them from the spark plug well. Be mindful not to damage the coil or the connector.
2. Anti-seize debate: There is ongoing debate regarding the use of anti-seize lubricant on spark plug threads. Most spark plug manufacturers recommend against it, stating that modern spark plugs have special coatings that prevent seizing. Additionally, anti-seize can act as an insulator, affecting the spark plug's heat transfer and potentially leading to over-tightening due to reduced friction, which can damage the spark plug and cylinder head threads. It's generally best to follow the spark plug manufacturer's recommendation or apply a very thin, consistent layer if you choose to use it.
3. Dielectric grease on boots: Apply a small amount of dielectric grease to the inside of the spark plug boots (the part of the coil that sits over the spark plug). This helps to seal out moisture, prevents corrosion, and makes future removal easier. Be careful not to get dielectric grease on the spark plug electrodes themselves.

Known issues

Fortunately, the 2015 Ram 1500 engines (3.6L Pentastar V6 and 5.7L HEMI V8) are not widely known for specific catastrophic spark plug issues like the two-piece spark plug breakage seen in some Ford 3-valve engines.

However, it's important to note the 5.7L HEMI V8 has 16 spark plugs – two per cylinder. This means you'll need to purchase and replace 16 spark plugs, not just 8. Ensure you account for this when budgeting and buying parts for your spark plug service.

Need plugs replaced? Find a shop on Repairius.