Cheap spark plugs, especially basic copper ones, can work fine for many cars, offering good conductivity but requiring more frequent replacement; however, they might not last as long or perform as well as premium platinum or iridium plugs in modern, high-performance, or complex engines, which benefit from the durability and consistent spark of expensive metals, though the best choice always depends on your specific engine's requirements.
You'll immediately notice your engine struggles when you don't use the right plug. It makes the combustion process inefficient because the plug cannot create the proper spark at the right time. The part may fail to ignite the fuel-air mixture completely, resulting in weak acceleration and reduced power output.
Expensive spark plugs buy longevity, consistency, and marginal gains in drivability--valuable for modern, high-performance, or hard-to-access engines. For basic older engines or frequent maintenance schedules, lower-cost plugs may be more economical.
Do different spark plugs make a difference? Yes, the different types have unique characteristics including heat ranges, sizes, terminal orientation, and more.
Upgraded spark plugs possess a finer centre electrode, allowing for a sharper, more concentrated spark. This promotes better combustion, improving throttle response, increased power output, and enhanced fuel efficiency.
Overheating: Overheating can cause the spark plug's electrodes to wear out more quickly. This is often due to issues like incorrect spark plug gap, poor fuel quality, too little fuel available for combustion, or engine overheating.
NGK is one of the most trusted names in ignition systems. Founded in Japan, NGK has been supplying OE spark plugs for Asian and American automakers for decades. Known for their consistency, NGK plugs are designed to perform well right out of the box and are built to meet or exceed OE specifications.
The most common signs of bad spark plugs include start-up trouble, rough idling, sluggish acceleration, declining fuel economy, engine misfiring, and engine knocking.
What does 'NGK' stand for? 'NGK' stands for 'Nippon Gaishi Kkabushiki-gaisha' which is the Japanese name of NGK Insulator Company Ltd., the company which NGK SPARK PLUG was spun-off from in 1936.
Generally, both brands offer impressive life, but NGK's iridium plugs tend to slightly outlast their Denso counterparts, particularly under harsh driving conditions.
A Noticeable Difference
Once your vehicle receives new spark plugs, you'll notice how much better your car feels while driving. You may notice such improvements as: Consistent and Optimal Combustion – Spark plugs that are in peak condition allow the combustion system to function at its highest potential.
Spark plug lifespan varies significantly by type — copper plugs may need replacement every 25,000-30,000 miles, while platinum or iridium plugs often last 100,000 miles or more.
You can expect to pay between $3 and $20 per spark plug, although some unique models can range even higher. And when you need anywhere between four and 16 spark plugs depending on what you drive, there's a chasm in what you can expect for pricing.
Generally speaking, expensive spark plugs offer better performance and last longer than copper spark plugs. In fact, products that use materials like platinum, like the ACDelco 41-962 Professional Platinum Spark Plug from Amazon, can go hundreds of thousands of miles without requiring replacement.
Waiting too long can lead to engine misfires, which are often felt as jerking movements when you accelerate. Severely worn spark plugs can cause rattling or knocking sounds, affecting your engine's overall performance and leading to costly repairs if left unaddressed.
Some of the best spark plug brands are NGK, Bosch, AC Delco, Denso, Champion, and GenuineXL. Factors you should consider when purchasing new spark plugs are the thread size, recommended use, and cost.
Look out for a machine cutting mark on the caulking (could indicate a counterfeit) Take a close look at the crimping portion of the plug. If you can see a machine cutting mark on it, be alert: this is indicative of a fake product.
An NGK 8 is hotter than an NGK 9 because, for NGK plugs, a lower number indicates a hotter plug, while a higher number signifies a colder plug; the number reflects the plug's ability to dissipate heat, not the spark's electrical energy. A hotter plug (like an 8) stays hotter and is better for fouling issues, while a colder plug (like a 9) runs cooler and prevents pre-ignition in high-performance engines.
Iridium Spark Plugs
It's as much as eight times stronger than platinum, so iridium can have a sharper center electrode that conducts a more durable, powerful spark. Iridium is much harder than even platinum, so it resists wear for up to 25% more lifespan.
Worn or damaged spark plugs can cause incomplete combustion, leading to engine misfires, rough idling, and reduced power. This not only impacts performance but also increases harmful emissions as unburned fuel exits the exhaust.
Symptoms caused by using imitation spark plugs include the vehicle's pull starting to feel heavy. Then, fuel consumption becomes more wasteful than it should be. Until the vehicle's power becomes weaker due to the effects of abnormal compression. However, the most fatal issue is the frequent occurrence of knocking.
If the engine is running to lean, the spark plug can look greyish white. If the engine is running to rich the spark plug will look black, sometimes a glossy black if it's really rich.
While plugs are pre-gapped from the factory, the gap may need to be adjusted for the vehicle that the spark plug is intended for. Those with modified engines must remember that higher compression or forced induction will typically require a smaller gap setting (to ensure ignitability under higher pressure).
The main disadvantages of iridium spark plugs are their significantly higher cost and increased fragility, requiring careful handling during installation, as the fine iridium tip can be easily damaged, negating benefits and potentially causing engine issues; they also can't be cleaned if fouled, meaning a fouled plug must be replaced, unlike some copper plugs.
Therefore, the ground electrode will wear out first. NGK gives them a life expectancy of 40-50k miles. But they have to temper their projections as driving conditions and motor modifications differ. Typically we have found you can expect 60,000 to 80,000 miles on an unaltered motor.