Going to tackle a plug and wire change after I finish changing out all my coolant lines. I've been browsing the forum and seen a few mentions of NGK tr55ix. Is this the plug of choice or are there better ones out there?

98 WS6.

 

Yep, TR55 Iridium is what I am running.

 

TR55IX here as well. Plug of choice for NA motors. If you plan on boosting or getting a nitrous system look at the TR6's.

 

For iridium, my choice would be AC Delco.

For conventional, I would pick NGK TR55.

 

X2. 41-110 ACDelco -- check out Amazon for good prices.

 

2 for Ac and 2 for NGK. You're not helping me hehe

 

The Delco Iridiums are made either by Denso, or NGK, depending on which supplier they are using at the time.

I don't know if they are the TR-55IX part number or not, but I use the NGK Laser Iridiums, only because they last MUCH longer than their non-Laser versions, and I HATE doing plug changes on these cars.

Unlike most of you I still have stock manifolds, and ALL of the Cali rated emissions equipment installed, so a plug change is an 8 hour ordeal, leaving me looking like I went 100 rounds with a wolverine, who had a rabid, mean, over-sized racoon as a tag team partner!

 

My car is stock as well. I only want to do this once.

 

Not sure what your definition of "much longer" is, but when I pulled my stock platinum plugs out at 103k miles, they looked great. The new plugs made only the most marginal of difference in terms of MPG, and driveability was unchanged. They probably could have gone for another 25-50k.

For a stock engine, with a well maintained (clean) MAF and properly functioning O2 sensors, I wouldn't hesitate to leave any iridiums in for 100k or more.

 

Just did this work ... x3 for AC Delco.

 

You are probably correct, but even the manufacturers themselves only claim 30K mile lives for their NARROW (0.4mm) center electrode iridiums (especially the Densos which claim an actual performance difference due to the thin electrode, at the expense of longevity), vs. their wider (0.6mm) center electrode iridiums which are rated for 60-100K.

 

The AC Delco iridiums state right on the box that they are a 100,000 mile plug. Not sure about the various iridium plugs that are offered directly from NGK or Denso.

 

These (the Delcos, regardless of who actually made them) are probably the next plug I will install when the time comes (I am sorry I did not use them at the last change).

 

Summit racing shows the NGK Iridium IX 7397. They show the NGK tr55ix for V6 cars. I'm prolly going to try the 7397.

http://www.summitracing.com/parts/ng...rd?prefilter=1

 

NGK Iridium IX Spark Plugs TR5IX # 7397