2015 Chevrolet Malibu: Spark Plug Type & Gap

Quick Reference: 2015 Malibu Spark Plug Specifications

Note: Always verify the part number and gap for your specific vehicle before installation. Aftermarket plug manufacturers may specify a slightly different gap.

Why the Right Spark Plug Matters

Choosing the correct spark plug is critical for engine performance, fuel economy, and longevity. It’s not just a matter of finding one that threads in; factors like heat range and electrode material are engineered for your specific engine.

• Heat Range: This refers to the plug's ability to dissipate heat from the combustion chamber. A plug that is too "hot" (doesn't dissipate heat well) can lead to pre-ignition, while a plug that is too "cold" can accumulate carbon deposits and misfire. The turbocharged 2.0L engine, for instance, requires a colder plug than the naturally aspirated 2.5L due to its higher combustion temperatures.
• Electrode Material: The 2015 Malibu engines use long-life Iridium-tipped spark plugs from the factory. Iridium is an extremely hard, precious metal that resists wear far better than platinum or conventional copper plugs. While copper plugs are excellent conductors, they have a much shorter service life (typically 20,000-30,000 miles). Platinum plugs offer a good middle ground, but for a modern engine with a long recommended service interval, sticking with the specified Iridium plug is the best choice to maintain performance and avoid frequent changes.

How to Gap a Spark Plug

Even though most premium Iridium plugs come pre-gapped, it is crucial to verify the gap before installation. Shipping and handling can easily alter this precise measurement.

1. Use the Right Tool: A "feeler gauge" or a dedicated wire-style spark plug gapping tool is the best choice. Avoid the simple disc-style "ramped" gauges, as they can put pressure on the fragile fine-wire electrode and damage it.
2. Check the Gap: Slide the correct wire or blade (e.g., 0.040" for the 2.5L) between the center and ground electrodes. It should have a slight drag, but not be too tight or too loose.
3. Adjust Carefully: If adjustment is needed, never pry against the center electrode. Gently bend the ground electrode (the L-shaped metal strap) by tapping the plug against a solid surface or using the adjustment slot on a gapping tool. Make tiny changes and re-measure until the gap is perfect.

Replacement Procedure Tips for 2015 Malibu

The 2015 Malibu uses a modern coil-on-plug (COP) ignition system, which eliminates the need for spark plug wires. Each spark plug has its own ignition coil sitting directly on top of it.

• Coil-on-Plug Removal: To access the plugs, you must first remove the engine cover. Then, unplug the electrical connector from each ignition coil and unbolt the coil (typically a single 10mm bolt). The coil can then be gently twisted and pulled straight up to remove it.
• The Anti-Seize Debate: The use of anti-seize compound on spark plug threads is a topic of debate. Modern ACDelco and NGK plugs often have a special metallic plating (like nickel or zinc) that provides anti-corrosion and anti-seizing properties. Applying additional anti-seize can act as a lubricant, leading you to overtighten the plug even with a torque wrench, potentially damaging the threads in the aluminum cylinder head. The best practice is to follow the plug manufacturer's recommendation. If the box says not to use it, install the plugs dry into clean threads.
• Dielectric Grease: It is highly recommended to apply a small amount of dielectric grease to the inside of the spark plug boot (the end of the ignition coil that fits over the plug's ceramic insulator). This prevents the boot from getting stuck to the plug, keeps moisture out, and ensures a good electrical connection.

Known Issues

The 2015 Chevrolet Malibu and its Ecotec engines are not generally known for the widespread, systemic spark plug issues seen in some other vehicles. Problems like the infamous Ford 3-valve Triton plug breakage (where a two-piece plug shell separates) or issues with specific ionization-sensing coils found on some GM V8 engines are not applicable to this model. Cracked porcelain is usually a result of improper handling or using the wrong socket, not a design flaw.

Sticking to the recommended torque specifications and using a proper spark plug socket with a rubber insert will prevent the most common installation-related problems.

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