Unnecessary spark plug replacement?

C

cpttz

Member
:
2015 CX-5 Touring AWD
UPDATE: Thank you all for replying me! I have all the new spark plugs installed anyway, and I will probably start a new thread to discuss about the performance of these new plugs. Here is a photo that shows what a spark plug looks like after one day of usage:

new_one_used_for_one_day.webp

Below are original post:
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I have a 2015 CX5 which now has about 73000 miles on it. According to the user manual, I should have the spark plugs replaced when it comes to 75000 miles.
I'd like to do things early, so I bought the new "OEM-like" spark plugs from Amazon (ILKAR7L11) and tools for installing them.

To my suprise, the old spark plug seems to be just fine, much better than I anticipated. How could a spark plug that has 73000 miles on it be in such a good condition! Of course, I failed to find any obvious flaws, but it's probably because I can't tell the real problems. So I took a photo of it comparing to a new one.

SP.webp

Do you think this replacement is totally unnecessary?

By the way, my OEM spark plugs are 'Mazda PE5S 18110"
 
Last edited:
What were you expecting a worn out spark plug looks like? Looks pretty old, dirty, to me. I mean, your engine wasn't throwing codes, which you don't want it to, so yes its still going to physically work, but the point of maintenance like this is to prevent problems before they happen. Don't overthink it, you did the right thing. :)
 
Old plug looks to be of a higher quality than the new one. Maybe we are just seeing difference between two different makers? NGK vs ND?

The iridium pad on the new plugs ground electrode looks odd (thin and ground down), as well as the weld job on the ground electrode.

The bar stock used to form the ground electrode on the new plug looks very "square".

The center electrode on the old plug has a nice taper to it where it meets the shoulder of the ceramic insulator. New plug does not.

The hex shell where the tool fits is also different between the two plugs.

Were the "amazon" plugs from a Mazda dealer on amazon?


attachment.php
 
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“OEM like” ?

Already the alarm bells in my head are going off. I hope you haven’t installed them. Return them and get the real thing.
 
Putting that Item number in Amazon returns NGK's.

So the old plug is on the right? Or did these both come out of your car? Because the one on the right needs replaced, no question.
 
cpttz said:
so I bought the new "OEM-like" spark plugs from Amazon (ILKAR7L11)
Click to expand...

Looks to be NGK spark plugs and not actual OEM sparkplugs which run more like $25+ a plug. I'm at 68k miles now, so planning to do mine soon as well on my 2014.

From the spark plug discussions I've been keeping tabs on on this site, there seems to be some differences of opinion on if the NGK's are of the same quality/performance or not. At this point I feel a little more comfortable spending the bit extra to get the OEM plugs. But I don't know. (dunno)
 
cpttz said:
I have a 2015 CX5 which now has about 73000 miles on it. According to the user manual, I should have the spark plugs replaced when it comes to 75000 miles.
I'd like to do things early, so I bought the new "OEM-like" spark plugs from Amazon (ILKAR7L11) and tools for installing them.

To my suprise, the old spark plug seems to be just fine, much better than I anticipated. How could a spark plug that has 73000 miles on it be in such a good condition! Of course, I failed to find any obvious flaws, but it's probably because I can't tell the real problems. So I took a photo of it comparing to a new one.

View attachment 219294

Do you think this replacement is totally unnecessary?

By the way, my OEM spark plugs are 'Mazda PE5S 18110"
Click to expand...

No, it's not necessary. I pulled plugs on my LS1 at over 80K miles and they looked great and gapped exact factory spec. I drove it another 70K miles and it did fine. My CX5 has 86k miles on it and OEM plugs and it's doing just fine, too.

If you ever do replace them, go OEM only. As I understand it, the plug is actually part of a feed-back system for the ignition stuff. I am unsure if Mazda tweaked the plugs from what you can buy off the shelf generic, or not, but I don't want to play that game.
 
Yeah changed my plugs at 70K miles or so. Plugs looked great. In hind sight I think 90k miles would even suffice.
 
I will always trust NGK unless someone besides Unobtainium, can give me a real reason not to. Always used them in my Saabs. Nothing else. Excellent quality.
And "oh I should have waited..." No. There's nothing wrong with changing your spark plugs a little early. It's called taking care of your car.
 
cpttz said:
⋯ so I bought the new "OEM-like" spark plugs from Amazon (ILKAR7L11) and tools for installing them.
⋯
So I took a photo of it comparing to a new one.

attachment.php

View attachment 219294
⋯
By the way, my OEM spark plugs are 'Mazda PE5S 18110"
Click to expand...
Thanks to your side-by-side comparison picture beteeen NGK ILKAR7L11 and factory Mazda PE5S-18-110 spark plugs. In fact this's the first time I saw such comparison picture. Why there's no any model imprint on ceramic insulator of NGK plug? I agree with mazdadude they look physically different which makes me believe NGK and OEM plugs can't be the same like some people claimed. I now definitely would use OEM PE5R-18-110 plugs although they cost a lot more than NGK's.

Here're a couple of old posts from OVTune (OrangeVirus Tuning):

OVT said:
Without getting into too much detail...you guys really...really..really want to use OEM plugs....
Click to expand...
OVT said:
the reason is because the ECU uses the ignition coils, which measure a resistance across the OEM plug for pre-ignition, and extremely low levels of knock retard the knock sensor cannot pick up, along with that it gives the ECU individual cylinder information, the spark plugs are actually used "as a sensor."

How it works exactly is proprietary information that I am not willing to share, you want to use OEM plugs.
Click to expand...

Yeah for some reason factory plugs are non-resistor type PE5S-18-110 like the other member just found out:

regtor said:
I went ahead and replaced them on our 2014 Grand Touring AWD after almost 5 years and 60k miles. I know the manual says 75k miles but I figure it was time given the high compression ratio SkyActiv engines and the lots of stop and go seen by this car (my spouse's hour long city commute).

I got the Mazda OEM plugs (PE5R-18-110) despite their high cost, given the experience of others on this forum. $25.82 each! https://www.shopmazdaparts.com/oem-parts/mazda-spark-plug-each-this-is-one-spark-plug-pe5r18110

You'll definitely need a 9/16" spark plug socket - the one size I did not have. I got a nice magnetic one with a swivel joint (GearWrench 3938) but it was too shallow for the Mazda plugs; I tapped in the magnet a bit and made it work (see my comment on Amazon). The plugs are pretty deep in the engine block so make sure you also have an extension for your wrench.

Very straightforward job: remove the cover, remove the bolts holding the ignition coils, unplug connector for each coil, and remove and replace plugs. Here is a pic of the old plugs. The electrodes looked in good condition with only some carbon on them. I expected some oil on the threads (no big deal) but the ceramic insulators had a bit too much crud (oil?). You can see where the rubber boot of the ignition coil fits on the ceramic insulator:

nvylkUX.jpg


After seeing them I'm glad I replaced them.
Click to expand...
 
ColoradoDriver said:
Looks to be NGK spark plugs and not actual OEM sparkplugs which run more like $25+ a plug. I'm at 68k miles now, so planning to do mine soon as well on my 2014.

From the spark plug discussions I've been keeping tabs on on this site, there seems to be some differences of opinion on if the NGK's are of the same quality/performance or not. At this point I feel a little more comfortable spending the bit extra to get the OEM plugs. But I don't know. (dunno)
Click to expand...
See my post above. And make sure to get a https://www.amazon.com/dp/ (commissions earned), not 9/16". Also a good quality 3/8" extension is needed for this socket or you may have a hard time to take this socket out of the plug hole.
 
Almost everyone uses NGK spark plugs in the Mazdaspeed community.
 
jthj said:
That’s an entirely different engine than Skyactiv though.
Click to expand...

Yes. The point I was trying to make is that we haven't heard of issues using NGK spark plugs. So I think NGK makes generally good spark plugs. I stay away from Denso spark plugs because there were one or two that cracked when they were trying to remove it.
 
Does anyone know who actually makes the OEM plugs?
Could it be NGK?
 
Repeat .. repeated ... repeat again: do NOT use any spark plug for CX-5 but OEM.
 
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