I'm wondering a few things about replacing spark plugs...

- what's better than OEM?
- Denso Iridium has a good rep but very expensive...what are other top of the line plugs??
- when should your originals be replaced if you're not having any visible problems?

 

Better in what way? "Better" is in the eye and butt dyno of the beholder. You say you have NO visible problems. If it ain't broke, why are you trying to fix it?
The manual says the OEM plugs are good for 100,000 miles, however, it wouldn't hurt to take them out from time to time and inspect them. If in doubt, then replace them. Since you've had good service from the OEM platinum plugs, why not just get the same? You won't achieve a miracle by going to something different.

 

OEM for me, nothing else.

Torque is very important...major engine damage WILL result if a plug comes loose

 

Plenty of info has been posted on this, including a table I posted that showed the average misfire rates of the better known plug designs. As others have said, OE design is hard to beat - i went to Denso iridium for long life and nbecause I went 1 range cooler. But the same spark performance can be had from their copper-based plugs - it is more around the electrode design. The misfires from the copper plugs looked almost exactlyt the same as the DI's, at 1/6 - 1/10 the price. I would consider the DI's in cars where getting tot he plugs is a big deal - on the S2000 it is so easy as to be irrelevant.

 

thanks for all the input guys...this is making me wonder how the spark plug industry has managed to survive. 100K sounds like long enough life to me so I'll be sticking to OE.