How to Distinguish the Material of Spark Plugs?
3 Answers
The central electrode core is the key to distinguishing spark plugs, and the specific methods are: 1. The thicker ones are standard type; 2. The thinner ones with a white color are platinum; 3. The thinner ones with a yellow color are iridium. What are the types of spark plugs: The main types of spark plugs include: standard spark plugs, insulator projection spark plugs, electrode spark plugs, seat spark plugs, pole spark plugs, and surface gap spark plugs. How spark plugs work: Spark plug working principle: The spark plug's ground electrode is connected to the metal shell, which is threaded into the engine block via the cylinder head. The insulator primarily serves to isolate the metal shell and the central electrode. The terminal nut is the part of the spark plug that contacts the high-voltage coil. When current passes through the terminal nut and the central electrode, it ionizes the medium between the central electrode and the ground electrode, generating a spark to ignite the air-fuel mixture in the cylinder.
Having driven for over a decade, distinguishing spark plug materials is actually quite straightforward. Copper ones are the most common, with a brass-like color, rough texture, and prone to rusting or turning black. Platinum plugs are shiny, silvery-white, with a smooth surface that resists oxidation. Iridium ones are more premium, appearing dark gray or pale gold, with refined appearance and super ignition efficiency. Nickel alloy plugs usually look dull gray and are more budget-friendly, but you can guess by color and weight – copper is the lightest, platinum slightly heavier, and iridium the most stable. Don’t just rely on appearance; check the small markings or model numbers on the spark plug, as codes often include material abbreviations, like PT for platinum. Spark plug material affects engine performance, so I recommend comparing options when replacing them—choosing the right material saves fuel and prevents engine shake. Inspect spark plugs every 30,000 kilometers or so, and with regular checks, identifying old material types becomes effortless.
As someone who frequently helps friends with car repairs, I distinguish spark plug materials mainly through models and markings. There are engraved codes on the side or top of the spark plug, such as NGK's LZKAR6AG, which indicates a copper core, 'Z' stands for platinum, and 'D' represents iridium. Different materials have distinct textures—copper cores are softer with a gritty feel, while platinum and iridium plugs are firmer, with smooth, even surfaces and a silver or gray-gold hue. Checking the packaging label, most brands specify the material grade. Budget cars typically use nickel alloy or copper, while luxury vehicles often feature high-end platinum-iridium combinations. Performance-wise, copper spark plugs ignite quickly but have a shorter lifespan, whereas iridium plugs are more durable. When removing or installing spark plugs, pay attention to the color change of the center electrode—oxidized or blackened ones usually indicate lower-grade materials. Don't skip this step when replacing spark plugs, as the right material can make your car's acceleration smoother.
