Starting in the mid-1990s, iridium-tipped plugs appeared. Iridium is even harder than platinum, so these plugs were intended to last longer. They are also claimed to slightly increase combustion ...

Although Accel has a 4.5-star rating on Amazon, one reviewer pointed out that these copper plugs only last about half as long as their platinum or iridium counterparts. It’s highly recommended ...

Ordinary plugs need replacing every 30,000 miles, but platinum and iridium spark plugs could last up to 55,000 miles. If your vehicle has symptoms like hard starting and poor idling, it could mean ...