The spark plugs you need depend on the engine in your Optima: the 2.4-liter GDI and the 2.0-liter turbo use high-quality iridium or platinum plugs from reputable brands, but the exact part number varies by engine code and market. Always verify the precise specification for your vehicle.
In this article, we break down the two engine options offered for the 2018 Optima, how to identify which one you have, and how to confirm the correct spark plug part numbers with OEM guidance.
Engine options in the 2018 Optima
Two engines were commonly available for the 2018 Optima, each with its own spark plug specification. Knowing which engine you have is the first step to selecting the right plugs.
- 2.4L GDI (non-turbo) – Typically uses iridium or platinum spark plugs that meet Kia’s OEM specifications, with NGK or Denso as common brand options.
- 2.0L Turbo – Also uses iridium or platinum spark plugs designed for turbocharged operation, with NGK or Denso as common OEM-compatible choices; exact heat range and gap must match the engine’s requirements.
Engine variant and regional specifications can influence the exact plug numbers, so the precise part you need should be confirmed through official sources for your car’s VIN and market.
Spark plug recommendations by engine
Across both engines, the standard approach is to use high-quality iridium or platinum tipped plugs from NGK or Denso, chosen to meet Kia’s original equipment specifications and to handle the engine’s ignition demands.
- 2.4L GDI – Iridium or platinum plugs that align with Kia’s OEM spec, commonly available from NGK or Denso.
- 2.0L Turbo – High-performance iridium or platinum plugs suitable for turbocharged operation, with brand choices typically NGK or Denso and a heat range tailored to turbo use.
Exact part numbers depend on the engine code and market. When in doubt, rely on official sources such as the Kia parts catalog or a dealer to avoid misfires or warranty issues.
Heat range, gap, and compatibility, at a glance
Choosing the correct heat range and gap is essential for reliable starting, smooth idle, and optimal combustion. Turbocharged and naturally aspirated engines often require different heat ranges and gaps, so do not substitute plugs without confirming compatibility with your specific engine.
Brand choices and cross-reference
NGK and Denso both offer direct cross-references to Kia’s recommended plugs. If you prefer one brand, you can typically use its equivalent as long as the heat range, thread size, and reach match the OEM specification. Always verify the exact part number for your VIN.
How to confirm the exact part number for your car
To ensure you get the right plug for your exact vehicle, follow these steps:
- Identify your engine code and trim, which can usually be found on the engine label or in the VIN information.
- Consult the official Kia owner’s manual or Kia’s service information for the spark plug part number corresponding to your engine code.
- Cross-reference the OEM part number with NGK or Denso catalogs to find approved substitutes if needed.
- Call or visit a Kia dealership parts desk and provide your VIN to confirm the exact spark plug part number for your car.
Using the exact Kia-approved plug ensures compatibility with ignition timing, heat range, and warranty coverage, and helps prevent misfires and degraded performance.
Summary
For a 2018 Kia Optima, the spark plug type depends on the engine: the 2.4L GDI and the 2.0L turbo both use high-quality iridium or platinum plugs from NGK or Denso, but the exact part number varies by engine code and market. To be sure, identify your engine, consult Kia’s official parts information or your dealer, and use OEM-recommended plugs with the correct heat range and gap. When in doubt, verify with your VIN to ensure you get the precise specification for your vehicle.