Replaced Spark Plugs @ 70,000 miles

[mazdadude]

I decided to change the spark plugs now as I am nearing 70k. After the change, the engine feels smoother, less vibration at idle, and acceleration/response feels improved.

I used the stock OEM replacement NGK Laser IRIDIUM #ITR5F13.

When removing the old sparkplugs, I noticed that two of them (cylinders #3, and #4) were already loose, and required no torque to remove.(mad)

Here is a close-up pic of one of the old plugs, they all look the same. There is some wear and deposits, but the gap was still in spec, and I think they could go to 100k miles pretty easily.

 

[skyhawk]

Thanks for the pic mazdadude. I will be checking mine (68,000km).

So lesson learned here for us mazda5 users is to check the condition of the sparkplugs
regularly. And not to believe dealers assurance that 'the sparkplugs are indestructible' and no need to check.

 

[flcruising]

The OM says to replace every 75k. Looks like a good thing to follow. Although, you can always carefully regap and clean them and probably get the same improvement.

 

[jimp]

have read where the plug tips are fairly brittle at 75K, so things could break fairly easily, easier to just install new ones if you've already pulled the old ones to inspect.

 

[flcruising]

The point was that if you are feeling cheap at the time (iridiums are not cheap), you can regap and gain a few more miles. Pulling spark plugs in any 4 cylinder is so simple, I wouldn't consider it a waste of time at all.

http://www.ngk.com/glossary.asp?kw=Should+I+gap+my+Iridium+Plugs?&manID=1&pt=

 

[Old Rotor]

That is the best closeup spark plug pic I have seen. I have about 25K on my '08 so it will be a few years till I have to worry about changing them but I worry if they're loose.

 

[jimp]

and my point is if you clean/re-gap a plug with 75K on it, and you crack the electrode, etc, you have the potential to do alot more damage to the engine than the cost of the plugs, but to each their own,

 

[flcruising]

I get your point...I guess I've done so many tune-ups that this seems trivial.

 

[Mntnbkr]

Is the OEM NGK iridium plug the best one to use or is there an aftermarket plug people have had good luck with? Tried Splitfire long ago on a honda...very good, but QC must have gone downhill - on my jetta one of them recently failed and my garage suggested going back to NGK OEM - they work great, smooth, no probs.
Always hoping and willing to consider there is a better than OEM brand option (OEMs often make a cheap choice), but satisfied with NGK if that's the best people have found.

 

[jimp]

stick with what the manual says for best overall performance.

 

[KBrian]

I'v always used NGK plugs and never had a problem FWIW

 

[Jetmech]

I would stick to OE for reliability and performance. I personally don't believe all the hype around spark plugs and believe the engineers knew what was best for fuel economy and reliabilty. That said does anybody know how much the OE plugs are?


Thanks

 

[mazdadude]

I would stick to OE for reliability and performance. I personally don't believe all the hype around spark plugs and believe the engineers knew what was best for fuel economy and reliabilty. That said does anybody know how much the OE plugs are?

Thanks

The average price with tax and shipping is about $12-13 a plug x 4 plugs, =$50

 

[flcruising]

I still don't understand what makes these OE iridiums so special. Especially @ $12+ per. I've easily gotten 60k+ out of NGK V-powers that are maybe $1.99 ea.

 

[mazdadude]

I still don't understand what makes these OE iridiums so special. Especially @ $12+ per. I've easily gotten 60k+ out of NGK V-powers that are maybe $1.99 ea.

I am not sure either, but for a car manufacturer to splurge on using them, while skimping everywhere on everything else, they must be something special. I would love to see a dyno run and emissions testing the entire range of sparkplugs, from the Champion Coppers, to the e3's, to the splitfires, platinums, irdiums, etc.

I am certain that they could easily have gone 100k miles. However if I waited that long to check them, I might have had some damage to the threads in the cyl head from the loose plugs.

I spoke with my friend about this, and he was not suprised about me finding the loose plugs. He is a certified dealer technician, and he told me that he sees this alot on engines with the longer duration spark plug intervals and tapered seat sparkplugs.

 

[flcruising]

See, I wonder if it's more to get the car out of warranty with less problems than for performance or emission related issues. The spark plugs have almost nothing to do with emission, as long as they are within the correct temperature range and aren't fouling. If they're sparking, the gap is set correctly, and the coils aren't crapping out, then it shouldn't matter what plug you run. The material type has more to do with longevity than anything else from what I've read. Some manufacturers (Denso Iridium) actually have replacement intervals @ 30k. Can you believe that?