Should I stay away from 2005 to 2008 (spark plugs)?

2019Chieftain-no-more · 2026-07-22T07:24:54-0400

I've been on the hunt for a S197 GT, but doing my research on common problems. The thing that is really bothering me is the spark plugs! I'm no mechanic but I can turn a wrench and like to do the simple things myself like breaks, oil changes and spark plugs (or so I thought).

One thought I have is if I find that perfectly priced and number of miles pre 2009 just have a Ford shop change the plugs from day one then deal with it again in a few years (not likely I'll be putting more than 3000 to 5000 miles a year on the car). The other thought is to pay a bit more and stay away from the earlier years.

Just looking for the thoughts of real-world owners. Am I over thinking this?

skwerl · 2026-07-22T08:20:01-0400

Back in 2005 Ford came out with engines using a new spark plug design. The spark plugs failed. So the spark plug manufacturers figured out the problem and fixed the defective plug design. That was 20 years ago. If the car you buy has the original plugs (unlikely) then it could be an issue. If the plugs have EVER been replaced it is no longer relevant.

StockishS197 · 2026-07-22T08:23:52-0400

I bought a 2007 a few years back that had the original plugs at 50k miles.

I pulled them and only one broke. The revised plugs don’t break anymore, so it’s a non issue.

It’s more of a mild inconvenience than anything.

GriffX · 2026-07-22T08:28:19-0400

You just need a left-hand torque wrench (or make it yourself) and you will not brake a spark plug. Of cause from year to year the cars got better, I would buy a later model.

08TorchRedShelbyGT500 · 2026-07-22T09:11:04-0400

Roughly speaking:

JC SSP · 2026-07-22T09:16:09-0400

It has been discussed on this forum several times. There is even a Ford TSB (Attached)

Several schools of thought on removal too... from zipping them out with impact gun, to quarter turn then lube creep overnight, etc. Either way, have the broken plug extractor tool handy just in case. If you in S. FL I will gladly lend you mine.

08TorchRedShelbyGT500 · 2026-07-22T11:00:06-0400

My Mar 2007 built Mustang Roush 427R had the 2-piece plugs, and within 1000 miles I pulled them and installed the Brisk one-piece plugs.

My May 27, 2008 built Mustang GT500 had already had the issues fixed, so when I pulled the plugs(out of precaution) and replaced them. They were already the one-piece plugs. Having owned 2 S197s, one had the plug and fuel tank filler issues, I vowed to buy a later model year so some of the early bugs got worked out.

My GT500 has been great so far without any issues. It was one of the last 4 GT500s built in the 2008 model year.

Forty61 · 2026-07-22T13:30:39-0400

Don't sweat it. It's a known issue with known fixes. If you're not confident in doing it then just pay a shop and make it their problem.

I changed what I believe were my cars original plugs at like 70k miles, took my time, got every one out in one piece.

2019Chieftain-no-more · 2026-07-22T19:18:40-0400

Thanks all for the responses, I'm old and get frustrated quickly lol no way I'd try doing the first change because god knows how long they've been in there. The current car I'm looking is a 2006 with about 50,000 on the clock. They probably have not been changed in those 20 years. I had read somewhere (as @StockishS197 suggested) that the updated plugs are changed, I'll have to verify that. If this 2006 looks and drives as nice as the pictures I may just get it and let the "stealer-ship" do it.

Bedouin · 2026-07-22T20:04:40-0400

2019Chieftain, lots of good info in the thread below, & a 4.6L V8 built after 11/2007 (see door jam sticker) should have the 1-piece plugs, but I wouldn't let that dissuade me from a clean '06-'09...later '08-'09 even better...& I'd definitely prefer to change them myself, only took me 2 hrs, & you'd do a more thorough job than a dealer, making sure no grit or debris fell into the cylinder, proper torque spec, using nickel anti-seize, etc.

https://www.s197forum.com/threads/broken-spark-plug-in-head-procedure.13432/page-10

Should I stay away from 2005 to 2008 (spark plugs)?

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