How Long Do Denso Iridium Plugs Last?
Denso Iridium Power series has an iridium center electrode with a traditional nickel ground electrode construction. Therefore, the ground electrode will wear out first. Typically we have found you can expect to get 60,000 to 80,000 miles on an unaltered motor. However, because gradual wear will "round-off" firing points over time, the concentrated firing power and voltage requirement benefits will be reduced. For this reason, Denso advises replacement after 30,000 miles.
Denso Iridium TT series features a 0.4mm iridium fine wire center electrode and 0.7mm platinum fine wire ground tip. Twin-Tip technology enables larger spark concentration and explosion, resulting in a more complete combustion and increased fuel economy. Tested to last beyond 100,000 miles, with minimal loss to performance.
Denso Long Life Iridium Plugs have iridium center and a platinum ground electrodes. If installed in a regular engine, they would likely last longer than most people keep their car (barring any motor problems that can cause premature plug death). All Denso long life iridium spark plugs are an OEM design, made for a specific engine. Some feature a special resistor or electrode design, depending on the OE requirements. In their OE application, Denso's long life plugs can last up to 120,000 miles.