How to Read a Spark Plug Heat Range Chart?
2 Answers
Spark plug heat range charts typically include numbers from 1 to 9, where 1-3 represent low heat range, 4-6 medium heat range, and 7-9 high heat range. Original equipment manufacturer (OEM) spark plugs usually come in heat ranges of 5, 6, and 7. The lower the number, the 'colder' the spark plug, meaning better heat dissipation. Below is an introduction to spark plugs: 1. Function of spark plugs: Spark plugs serve to conduct the high-voltage electrical pulse from the ignition coil into the combustion chamber, using the electrode's spark to ignite the air-fuel mixture, thus completing combustion. 2. Types of spark plugs: Common spark plugs are categorized into resistor spark plugs, platinum spark plugs, and iridium spark plugs. Generally, resistor spark plugs have a lifespan of 20,000 kilometers, platinum spark plugs last up to 40,000 kilometers, while iridium spark plugs can endure between 60,000 to 80,000 kilometers.
When I first started changing spark plugs myself, I ran into trouble because the heat range was wrong, causing difficulty starting in winter. The heat range of a spark plug is the small number in the model code—the smaller the number (like 4), the slower the heat dissipation, making it suitable for gentle driving; the larger the number (like 9), the faster the heat dissipation, making it suitable for high-performance cars. When checking the reference chart, first find your vehicle manual or the spark plug brand's website, then input your car's make and model to see the recommended heat range. Driving style also affects the choice—for example, frequent highway driving or hot weather calls for a higher number, while city commuting suits a lower number. Choosing the wrong heat range carries risks: too low can cause overheating and carbon buildup, while too high can lead to slow cold starts. I always double-check the chart when changing spark plugs to ensure they match the environment. Vehicle modifications like turbochargers also require a higher heat range, and the reference chart helps avoid mistakes.
