sparkplug replacement

[denperkins]

I'm looking at replacing the sparkplugs on my 95 Q45. While researching NGK plugs I came upon both platinum (PFR5G-11) and Iridium IX (BKR5EIX-11). NGK states that the Iridium can be left in for 100,000 miles vs 60,000 for the platinum. Can the Iridium be used in my car and are they worth it seeing as how much trouble they are to replace.

[Q45tech]

The orginal plug replacement interval was for a brand new engine, the 2nd and 3rd and 4th sets of plugs will each have a declining interval due to ring and valve stem seal wear.

For a while I kept samples of the 60k and 120k and 170K and 210k plugs and realized that each looked progressively worse.

Plug life depends on engine condition and the type of driving you do.

Whenever you exceed 60k you add the raisk of plug threads fouling into heat threads.

At some mileage platnium maybe switched to copper because you will be changing plugs every 30k.

My 300K plugs were changed at 40k now I'm at 312k and looking forward to a 30k change.

[qship96]

guess my engine must not be wearing at all,as the first set of replacment plugs were installed at 69,000 miles......... still working well at 187,890 miles { 119,000 miles on them} no misfires,no CEL even with super-sensative OBD 2 watchdog checking

[Q45tech]

I was referring to magnified observation of electrotrodes and actual measurements of gap, and measured power balance numbers..................lack of a misfire is so far removed from the definition of a suitable plug. The oem coil on plug system will fire a plug almost without electrodes at normal rpm...........things get dicey above 6,500 rpms.

187k is just getting broken in if oil and air filters are replaced at frequent intervals.

It seems that even with the finest care that 250k starts the decline......really a function of the number of cold starts [below ~~ 50F] and the time for lubricity to ramp up to functioning oil.