mechtech2:
Here is the info from sparkplugs.com :
"A traditional iridium plug such as a Denso IK20 or NGK ZFR6FIX-11 both have iridium center electrodes, however the ground electrodes are the traditional nickel construction. The ground electrode will wear out first. The manufacturers are saying 40,000 to 60,000 miles on iridium plugs. 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. (One of our trucks has had the Denso's in for 76,000 miles. We examined 2 of the plugs, they had some minor spooning on the ground electrode. Put them back in and will likely change them in another 5,000 miles.)
Both Denso iridium racing plugs and some NGK iridium racing 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). But, these usually come in heat ranges too cold for an unaltered motor and are usually used in racing applications where all bets are off.
For the traditional automotive market, the longest lasting plugs are the NGK "IFR" series and the Denso "SK" series. These have iridium center and platinum tipped ground electrodes, however, these are extremely limited in application as they only manufactured these in a couple of heat range configurations."
Here is the info from sparkplugs.com :
"A traditional iridium plug such as a Denso IK20 or NGK ZFR6FIX-11 both have iridium center electrodes, however the ground electrodes are the traditional nickel construction. The ground electrode will wear out first. The manufacturers are saying 40,000 to 60,000 miles on iridium plugs. 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. (One of our trucks has had the Denso's in for 76,000 miles. We examined 2 of the plugs, they had some minor spooning on the ground electrode. Put them back in and will likely change them in another 5,000 miles.)
Both Denso iridium racing plugs and some NGK iridium racing 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). But, these usually come in heat ranges too cold for an unaltered motor and are usually used in racing applications where all bets are off.
For the traditional automotive market, the longest lasting plugs are the NGK "IFR" series and the Denso "SK" series. These have iridium center and platinum tipped ground electrodes, however, these are extremely limited in application as they only manufactured these in a couple of heat range configurations."
