2020 Subaru Crosstrek Spark Plug Type & Gap

Quick Reference

Why the right plug matters

Choosing the correct spark plug for your 2020 Subaru Crosstrek is crucial for optimal engine performance, fuel efficiency, and longevity. The spark plug's primary function is to ignite the air/fuel mixture in the combustion chamber, and several factors—including heat range, electrode material, and gap—play a critical role in this process.

Heat Range

Spark plugs are designed with a specific "heat range," which refers to the plug's ability to dissipate heat from the combustion chamber. A plug that's too "hot" (dissipates heat slowly) can lead to pre-ignition and engine damage, while a plug that's too "cold" (dissipates heat too quickly) can cause fouling and misfires. The OEM-recommended plugs for the 2020 Crosstrek are carefully selected to maintain the ideal operating temperature for your engine.

Electrode Metal: Iridium vs. Platinum vs. Copper

Modern vehicles, including the 2020 Subaru Crosstrek, typically use iridium or platinum spark plugs due to their superior durability and performance compared to traditional copper plugs. While copper is an excellent conductor, it wears down much faster, requiring more frequent replacement.

• Iridium: These are the most advanced and durable spark plugs, often lasting 100,000 miles or more. They feature a fine-wire iridium center electrode and often an iridium-enhanced ground electrode, providing a strong, consistent spark and excellent wear resistance. The OEM plugs for your Crosstrek are iridium, designed for extended service intervals.
• Platinum: Platinum plugs offer a step up from copper, with longer lifespans (typically 60,000-80,000 miles) and better performance. They usually have a platinum disc welded to the center electrode.
• Copper: While still used in some older or high-performance applications that benefit from copper's conductivity, copper plugs have the shortest lifespan and are not recommended for your Crosstrek's original equipment design.

How to gap a spark plug

Properly gapping a spark plug ensures the optimal distance for the spark to jump, providing the strongest possible ignition. While many iridium and platinum plugs come "pre-gapped" from the factory, it's always a good practice to double-check the gap before installation. For the 2020 Subaru Crosstrek, the recommended gap is 0.044 inches (1.1 mm).

To gap a spark plug:

1. Use the right tool: A wire-type spark plug gapping tool is generally preferred for iridium and platinum plugs to avoid damaging the fine-wire electrode. Avoid using a coin-style gapping tool, as it can be too aggressive.
2. Check the gap: Insert the appropriate wire gauge into the gap between the center and ground electrodes. It should slide in with a slight drag.
3. Adjust if necessary: If the gap is too small, gently bend the ground electrode outwards using the gapping tool's adjustment notch. If the gap is too wide, gently tap the ground electrode on a hard surface to close it incrementally. Be extremely careful not to touch or damage the delicate center iridium electrode.

Replacement procedure tips

Replacing spark plugs on a Subaru Boxer engine can be a bit more involved than on an inline engine due to the horizontally opposed cylinder layout. Here are some tips for your 2020 Crosstrek:

1. Access: The spark plugs are located on the sides of the engine, requiring removal of the airbox on one side and potentially the battery or other components on the other for better access. Consider using universal joint sockets or wobble extensions.
2. Coil-on-Plug Removal: Your Crosstrek uses a coil-on-plug (COP) ignition system. Each spark plug has its own ignition coil directly mounted on top. To remove, disconnect the electrical connector, then unbolt the coil (usually one bolt) and gently pull it straight up. Be careful not to damage the coil or the boot.
3. Anti-Seize Debate: There's ongoing debate about using anti-seize on spark plug threads. For spark plugs with nickel-plated shells, like the OEM NGK plugs, anti-seize is generally not recommended by the manufacturer. The nickel plating provides adequate anti-seize properties, and adding more can lead to over-torquing and potential damage to the cylinder head threads. Follow the manufacturer's recommendation.
4. Dielectric Grease: Apply a small amount of dielectric grease inside the spark plug boot (where it contacts the ceramic insulator of the plug). This helps to seal out moisture, prevents the boot from sticking, and insulates against voltage leaks. Do not apply it to the spark plug threads or electrodes.
5. Torque is Key: Always use a torque wrench to tighten the new spark plugs to the specified torque of 15.0 lb-ft (20.0 Nm). Over-tightening can damage the spark plug or, more severely, strip the threads in the aluminum cylinder head. Under-tightening can cause the plug to loosen, leading to misfires and potential damage from hot combustion gases escaping.

Known issues

Fortunately, there are no widespread or notorious spark plug-related issues specific to the 2020 Subaru Crosstrek's FB20D or FB25D engines, unlike some engines of other manufacturers (e.g., the infamous 2-piece spark plug breakage on certain Ford 3-valve engines). Sticking to the recommended OEM spark plugs and following proper replacement procedures will help ensure trouble-free operation.

Need plugs replaced? Find a shop on Repairius.