Why buy expensive platinum spark plugs when cheaper copper ones exist? – Jalopnik

The reason why you should always use the manufacturer’s approved spark plug type has to do with the ignition system of your car’s engine. Newer vehicles with electronic distributor-based ignition systems often operate on longer-lasting platinum plugs. These spark plugs have platinum discs attached to the tip of the center electrode. Because platinum is a harder metal than the nickel alloy of copper plugs, they wear more slowly and can last 60,000 to 100,000 miles.

Additionally, platinum burns hotter and has a higher melting point, giving it the ability to burn carbon deposits and reduce pollution. You should avoid switching to copper plugs if your car runs on platinum plugs, as the former are more likely to wear out and need to be replaced more often, which can cause loss of performance and engine damage.

Vehicles with electronic waste spark ignition generally require double platinum spark plugs. Waste spark ignition engines (like the venerable Mitsubishi 4G63 that powered most Lancer Evos) require spark plugs with platinum discs on the center and side electrodes to capture the reverse spark created when one cylinder is on the compression stroke and the other on the exhaust stroke (which is one of the four engine strokes in an internal combustion engine). At that stage the spark travels from the side electrode to the center.

If your goal is to save money, you may end up spending more if you insist on using copper spark plugs in an engine that requires platinum. Platinum spark plugs cost about $6 to $8 each (which isn’t much more than copper at $5 each), and they can last three to four times longer. If you use copper, you will likely pay more in the long run due to the more frequent replacements.

Despite their name, copper plugs have a nickel alloy electrode welded to the solid copper core, and the point is to make the copper core last as long as possible. Unfortunately, the biggest drawback is that copper is a softer metal and wears out more quickly than platinum-infused spark plugs, and they typically need to be replaced every 20,000 to 20,000 miles.

If the vehicle owner’s manual recommends copper plugs, stick to that and resist the urge to upgrade to more expensive platinum or iridium plugs. Why? Some motors are specially designed to run on copper plugs. And for some applications or certain makes and models, copper plugs are classified as high-performance plugs, primarily due to their inherent ability to conduct more heat from the combustion chamber.

While there are options to upgrade from copper to platinum or even more expensive iridium plugs, it is important to select the correct voltage, heat range and size to ensure instant compatibility and trouble-free performance. Constantly running an engine with the wrong spark plugs can lead to misfires, excess carbon deposits, poor fuel economy and expensive repairs.