bees

Got it, thanks for the clarification! Did some more searching and the plugs are nickel plugs with a copper core as you stated.

PureDrifter

iTrader: (10)

Partially correct.

Copper is simply the best conductor when compared to platinum or iridium. It offers up the hottest spark with the most power behind it. It does not, however, last nearly as long as iridium or platinum plugs. Most performance vehicles will run copper plugs for this exact reason.

Read up.

aptoslexus

I have read up. Your "copper" plugs are only copper in the center electrode, as are all plugs. They have to be coated with metal that will survive the combustion chamber, because copper itself won't. That is straight from the manufacturer. It's the quality of the outside material that determines the life of the plug, and obviously, iridium is top of the heap.

Verbatim from NGK: '"Copper spark plugs" is a term mistakenly used for a standard material spark plug. A standard material spark plug traditionally uses a nickel-alloy outer material fused to a copper core.
Almost all spark plugs use a copper core center to conduct the electricity, jump the gap, and promote heat dissipation. However, as an outer electrode material, copper would not be a good choice,
as it is soft and has a low melting point (resulting in a plug that would last minutes, not miles). All NGK spark plugs, including precious metal iridium and platinum, have a copper core.

When one talks in terms of nickel alloys, platinum and iridium, one is referring to its durability, or how long a spark plug will last before it needs to be replaced.' http://www.ngksparkplugs.com/pdf/dyk_5points.pdf