NGK 97566 Spark Plug

NGK Laser Iridium Spark Plug for Mercedes-Benz

NGK 97566 is a Laser Iridium High Ignitability spark plug built for select Mercedes-Benz applications that call for precise ignition performance and OE-style service intervals. It uses an iridium center electrode, copper core construction, and a 0.028 in pre-gap to support consistent spark delivery in modern turbocharged and performance engines.

Key Features

• Laser Iridium High Ignitability design for stable ignition performance
• Iridium center electrode tip with copper core construction
• Thin square ground electrode tip design with single ground electrode
• Pre-gapped to 0.028 in for listed applications
• 1000 ohm resistance and flat seat design
• 12 mm thread diameter, 1.06 in reach, and stud terminal type
• NGK part number 97566, also identified as SILZKFR8F7S

Product Details

NGK’s Laser Iridium High Ignitability line is engineered for vehicles that rely on a fine-wire iridium firing tip and OE-level fitment control. This spark plug is specified across a wide range of Mercedes-Benz models, including AMG performance variants and luxury SUVs, where accurate ignition timing and consistent combustion matter. The copper core design helps manage heat transfer, while the 8 heat range and flat seat configuration align with the listed factory applications. NGK 97566 is a direct replacement choice for drivers servicing Mercedes-Benz C300, GLC300, GLE350, GLA250, and other listed models.

This part cross-references Four Seasons 97566 for the same application.

Common Reasons for Replacement

• Rough idle or inconsistent combustion at startup
• Misfire codes related to worn or fouled spark plugs
• Reduced throttle response under load
• Hard starting or extended crank time
• Service interval replacement on Mercedes-Benz models with high ignitability plugs

Installation Notes and Tips

Verify engine code, plug reach, thread diameter, seat type, and gap before installation. Use the listed 0.028 in gap only where specified by the vehicle application, and follow the manufacturer service procedure for torque and removal on aluminum cylinder heads. Confirm the correct Mercedes-Benz fitment by year and model before ordering, especially on AMG and high-output variants.

Quality Assurance

NGK is a major OE spark plug supplier with more than 80 years of automotive experience and broad coverage across domestic and import applications. The brand manufactures to original equipment standards and supports North American and global distribution for consistent product availability and application accuracy.