When to replace OE spark plugs?

[Klutch9]

My Sedona recently rolled over 80k miles. At 100k miles, the OM recommends replacing the iridium plugs. On this motor, like many other transverse V6s, the rear plugs are a bear to get at. Should I just suck it up and tear into it at 100k, or wait til I get a stumble in the idle? Do plugs degrade slowly over time? Or are they either working properly or not? I've heard of many people going well over 100k on iridium plugs with no noticeable change in fuel economy or performance.

 

[147_Grain]

Personally, I'd change the plugs now with NGK Laser Iridium.

 

[Lillikai]

I would go with what the owners manual says and change em at 100k. That's what I did for both vehicles in my sig and they work great. Absolutely no problems and the Fusion now has 160k on it, still running strong!

Also try to get as close as you can to factory standard parts. Ive got motorcraft in the fusion and acdelcos in the saturn.

 

[mclasser]

I'd wait til the recommended 100K.

 

[spasm3]

100k, why bust your knuckles on the back bank 20k before you have to?
Replace them at 100k with the same or better. Be careful gapping them, you don't want to mar or break the iridium electrode. I check mine carefully, i use a light oil (wd 40) on my round gap gauge.

 

[WobblyElvis]

I have 150,000 on the original iridium plugs in my 06 chevy. They may never wear out. I think they will give some warning as they start to fail. Perhaps they'll misfire while under load at first. I would use the exact same plug if possible.

 

[slacktide_bitog]

Wait at least until 100k.

The only time you should do them before that is if you're leaking oil and need to replace the valve cover gaskets and spark plug tube seals.

 

[HKPolice]

If you don't notice any hiccups then I would wait until 120K miles. I'm assuming the OEM plugs are NGK laser iridum or Denso iridium long life? Those plugs are rated by the manuf for upto 120K even though the car manuf recommends only 100K.

I recently took out the plugs in my 05 Matrix and the gap is almost factory spec after 84k miles.

 

[moklock]

With iridium tips 100K should be fine. I have pulled a set of AC (really NGKs) out of a 5.3 Chevy with almost 120K on them before. Came out easy and were still in very good shape.

The platinum tip plugs I used to change early also but iridium really does last and is well worth the price. Whatever U take out put back the same the biggest problems usually come from those that cheap out on replacement plugs.

 

[BikeWhisperer]

When I had my Silverado I waited until 100k miles as per the owners manual. When I pulled the "old" plugs they were clean and 0.002" out of spec on the gap...they probably had another 100k in them!

 

[Merkava_4]

Pull one of them out and check the gap.

 

[bbhero]

I changed mine at 100k.. And your motor is similar in layout in my I bet. The three plugs closest to the firewall had the throttle body and intake manifold had to be taken off too. Big pain. You can either change them at 100k miles or wait for the first stumble and change them then. I did that with my Ford Fusion and it started that at 105k. Changed them pronto after I noticed that. It is obvious to me that other people have gone well longer with their iridium plugs. Way way better than the copper plugs, no doubt in that.

 

[hansj3]

My '12 soul has no mileage spec on plugs. Neither on mitchel or in the manual. Maybe KIA has a spec, but their supposed to share it with mitchel..as long as it isn't a 3v trition I wouldn't worry

 

[Doog]

I change my plugs at 120k-140k in my Toyotas. 100k is the manufacturers recommended interval but after doing one set at 100k and having the plugs coming out like new I added some mileage.

 

[mrsilv04]

I changed my 100,000 mile plugs on my Silverado at 85,000 miles.

Not so much that it was 85,000 miles, but that they'd been in there for 11 years.

 

[Doog]

Originally Posted By: mrsilv04

Not so much that it was 85,000 miles, but that they'd been in there for 11 years.



Yeah but they like it in there.........

 

[Chris142]

I'd replace them before they start to missfire. Missfires can ruin your $2000 cat converters.

 

[SteveSRT8]

We have run OEM plugs in our fleet trucks to well over 200k without misfires. Most vehicles will quickly light the MIL if any misfire is detected, so the plugs will tell you.

Iridiums should last a minimum of 100k miles...

 

[pb]

guys, while the plugs may be fine, there is the concern that seizing may occur at long durations. i think it's absurd to expect 100k unless your taking it to the dealer for the plug change.

 

[hattaresguy]

If you plan on keeping the vehicle for less than 150k I would never change them.

I changed my last set of plugs on my Silverado at 90k and they looked new. I never plan on touching modern plugs again unless one fails.