Spec R

the main difference is in how long they last in a well tuned engine. on our inline 4's its super easy to change plugs so the extra time interval for service isnt a big deal, but on cars like lets say the Solara, to get to the back 3 plugs, you have to take off the intake manifold. not fun.

v6_accord_jerz

I would just get the oem platinum plugs.

kevyt

2001TEGGSR, That is a good link. Thanks. I removed my Denso Iridium IK20's from my stock 96 GSR and I am not sure what I should use. I was getting 33 mpg and the plugs are shot! I assume I have 5 years on the plugs.

CraigK

I researched a lot about the new plug types and came to the conclusion that the very expensive Iridium plugs, may, under certain high performance conditions, provide a marginally improved spark. But they do NOT last long. Platinum plugs are now relatively inexpensive, give excellent performance, and last a VERY long time. I now use Autolite DOUBLE platinum plugs (APP#, not AAP#) in all my vehicles, at ~ $4 each. (I think it's important to get the double platinums, so both ends of the spark are the hard platinum.) FYI - My motors are stock, or close to it.

BTW, the plugs I pulled from the 91 Teg I just bought were highly eroded (161k), and had gaps of .065-.070"!

CraigK

Spec R

i'll chime in again on this topic...now with a bit more experience.

on lightly modded (bolt ons, stock compression, no forced induction) NA B-series engines, stock replacement coppers are fine.

its when you start bumping up compression and/or adding forced induction that plug choice start to play a role. u really have to close up the plug gap on force induction engines and plug heat range also becomes a factor. when brand new platinum vs iridium perform relatively the same, but like it was said before, its how long that brand new performance lasts. the iridiums last longer in a harsh engine environment, and are often OEM spec for higher performance engines.