2018 Toyota Tundra Spark Plug Type & Gap

Quick reference

Why the right plug matters

Your 2018 Toyota Tundra is a workhorse, and its spark plugs are crucial to its performance and fuel efficiency. Using the correct spark plugs, specified by Toyota, ensures optimal combustion. There are three main types of spark plug electrode materials: copper, platinum, and iridium.

Copper plugs are the cheapest and conduct electricity well, but wear out quickly due to their softer nature. They're rarely used as OEM in modern engines.

Platinum plugs offer a longer lifespan than copper. They are a step up in durability, extending replacement intervals considerably.

Iridium plugs, like those specified for your Tundra, are the gold standard. Iridium is incredibly hard and has a very high melting point, allowing for very fine electrodes that produce a more consistent and powerful spark. This leads to better fuel economy, smoother engine operation, and much longer service intervals—typically 100,000 miles or more.

Using a spark plug with the incorrect heat range can also cause problems. A plug that is too "cold" won't get hot enough to burn off carbon deposits, leading to fouling. A plug that is too "hot" can overheat, causing pre-ignition or detonation, which can severely damage your engine.

The gap between the center and ground electrodes is critical for a strong, consistent spark. Too wide, and the spark may be weak or misfire. Too narrow, and the spark may be too small, leading to incomplete combustion.

How to gap a spark plug

Most modern iridium spark plugs, like those for your 2018 Tundra, come pre-gapped from the factory. It is generally advised not to attempt to gap iridium plugs. The fine iridium electrode can be easily damaged. If you must check the gap, use a wire-type gap tool, not a disc-style tool, which can exert force on the side of the electrode. Gently slide the wire gauge through the gap to verify it matches the specification. If the gap is incorrect, it's usually best to replace the plug rather than attempt to adjust it, especially with iridium. If you do attempt to adjust, only bend the ground electrode very slightly.

Replacement procedure tips

Replacing the spark plugs on your 2018 Toyota Tundra 5.7L V8 is a manageable DIY task, but precision is key. Your Tundra uses a coil-on-plug ignition system, meaning each spark plug has its own ignition coil mounted directly above it.

1. Preparation: Ensure the engine is cool. Disconnect the negative battery terminal.
2. Access: You'll need to remove any engine covers to access the ignition coils.
3. Coil Removal: Gently disconnect the electrical connector from each coil. Press the tab on the connector and pull. Then, unbolt the coil (typically a 10mm bolt) and pull it straight up. Some coils might be a bit stubborn due to vacuum-like suction. A slight twisting motion can help.
4. Plug Removal: Use a spark plug socket (typically 5/8" for Toyota) with an extension and ratchet. Turn counter-clockwise to loosen. Be slow and careful to avoid stripping the threads.
5. Anti-Seize Debate: There's ongoing debate regarding the use of anti-seize on spark plug threads. For modern plugs with plated shells, manufacturers often advise against it, as the plating provides sufficient anti-seize properties and anti-seize can alter torque readings. Toyota does not specify anti-seize for your Tundra's spark plugs. If you choose to use it, apply a very thin coat and reduce the torque specification by about 20% to compensate.
6. Installation: Hand-thread the new spark plugs into the cylinder heads to avoid cross-threading. Once finger-tight, use a torque wrench to tighten to the specified 13 lb-ft (18 Nm). Do NOT over-tighten, as this can strip threads in the aluminum cylinder head, leading to extremely costly repairs.
7. Dielectric Grease: Apply a small amount of dielectric grease to the inside of the spark plug boots before reinstalling the ignition coils. This helps prevent moisture entry, insulates the connection, and makes future removal easier. Push the coil firmly onto the plug until it seats, then re-bolt and reconnect the electrical connector.
8. Final Steps: Reinstall any removed components and reconnect the battery.

Known issues

Fortunately, the 5.7L V8 (3UR-FE) engine in the 2018 Toyota Tundra is known for its robust design and does not have widely documented, recurring spark plug-related issues similar to the Ford 3-valve engine's problems with two-piece plugs breaking or GM's ionization-sensing coil issues. As long as the correct genuine Toyota or specified aftermarket iridium plugs are used and replaced within the recommended interval, and properly torqued, they should provide reliable service.

Need plugs replaced? Find a shop on Repairius.