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Longest spark plug use?

Old 09-13-2013, 12:56 PM
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Longest spark plug use?

I'm at 38kmi now, with no misfires. I'm wondering if I'll be able to make it to 40kmi.
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Old 09-13-2013, 12:59 PM
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I change every year regardless of miles. have you checked the spark gap? Just because there aren't misfires doesn't mean that it is efficiently burning. The oem coils can only ignite a gap so large.
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Old 09-13-2013, 01:02 PM
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Nah, I haven't touched the plugs since I bought the car 4 years ago. There's a bit of a sulfur smell when the engine is cold, but that's because I use Group 5 engine oil, which has exposed sulfur atoms at the ends of the oil molecules. No smell at all when the engine is hot, and no soot on the bumper either.
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Old 09-13-2013, 05:10 PM
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My neighbor used his right up until it flooded, then flooded the cat, then cat heated, then car caught fire.. I guess you could say he used them right up until the car died... He got out OK. That makes them lifetime plugs....

Last edited by 04Green; 10-03-2013 at 11:09 AM.
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Old 09-13-2013, 05:22 PM
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^^ the winner of this contest is not exactly winning.
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Old 09-13-2013, 05:44 PM
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I think Mazda says in Owners Manual that they can go for 60K KMS (36K Miles)....but exactly how efficient are they working at that age?..

What kind of extra load does a widening gap on long use spark plugs have on the reliability and efficiency of the ignition coils?..

As previous owners of any Rotary will tell you Ignition and Spark Plugs are a critical service part of any RE's longevity/performance/mileage and use...

Nothing has changed in the RX-8 to make me think any differently, yes spark plugs / coils are better...but.
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Old 09-13-2013, 06:16 PM
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Wow, so you have knowingly neglected your car's health? Not that I'm one to be paranoid, but not only have you gone way beyond what's normal for wear on the plugs (not unheard of), but you haven't even verified if they, or the rest of your engine/exhaust system is in any danger of causing severe problems (ie kill the cat/coils/engine, or worse).
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Old 09-13-2013, 06:21 PM
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Originally Posted by 04Green View Post
My neighbor used his right up until it flooded, then flooded the cat, then cat heated, then car caught fire.. I guess you could say he used them right up until the car died... He got out OK.
I'd say he is the "winner" according to the thread criteria .
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Old 09-13-2013, 07:19 PM
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I believe the owner's manual says to change at 32k or 38k miles? I replaced mine at 25k and felt like that was way too long.
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Old 09-17-2013, 11:56 AM
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I'm getting around to it. I've had other crap to worry about lately and my car has been nowhere near the top of that list. I'll probably have it done at the next oil change, coming up soon. I was just curious what's the longest anyone had managed to use a set of sparkplugs without noticeable problems.

Last edited by fyrstormer; 09-17-2013 at 12:00 PM.
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Old 09-17-2013, 12:41 PM
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Just get them changed, you don't want to be this guy:

https://www.rx8club.com/series-i-tro...e-help-244839/

a flame broiled car will really give you something to worry about.
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Old 09-17-2013, 12:53 PM
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mine made it to 63K miles before flooding
I really abused NA8 and it never let me down
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Old 09-17-2013, 06:15 PM
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60K plus until it flooded also. Then I found out Mazda was not donig PM's like we brought the car in for.

On top of that I replaced my coils when I rebuilt the engine at 138K. Up until then stock coils from 2005.
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Old 09-24-2013, 01:17 PM
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I'm not going to push it as far as 60kmi. I know the sparkplugs in a rotary have to deal with a lot more crap than the sparkplugs in a piston engine. I was just curious how close to the edge I am.

I'll probably get BHR coils when I replace the sparkplugs. I just wish I could sell the damn house that's making me lose money every single month.
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Old 10-02-2013, 06:45 PM
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You'll all be happy to know I finally got around to ordering a set of new sparkplugs from MazMart. I'll take pictures of the used ones so you can marvel at my stupidity for not changing them sooner.
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Old 10-02-2013, 10:07 PM
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you will notice it gets harder and harder for the engine to crank over as the spark plugs get dirtier and dirtier.
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Old 10-04-2013, 10:08 AM
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I hit 40kmi about a week ago. Thus far I haven't had any issues with starting.
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Old 10-06-2013, 07:16 PM
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Okay, here are pictures of my sparkplugs. Both sets looked the same, so I didn't bother to take pictures of both sets.





The green on the leading sparkplug is a new thing to me; I've never seen that before. Other than that, they look pretty normal for an engine that burns oil. Do you agree?

The engine idles a little smoother with the new plugs, and the engine sound on the highway is a little smoother too. It's a subtle yet noticeable difference.

Last edited by fyrstormer; 10-07-2013 at 01:17 AM.
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Old 10-06-2013, 07:42 PM
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This is a bit like those "this is your brain... this is your brain on drugs" ads. Good call on changing them
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Old 10-06-2013, 08:33 PM
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According to the NGK website, the green stuff is oxidized electrode material. I don't know how electrically-conductive the oxide is, but the leading plugs look like they were getting close to bridging the center electrode to the housing, at which point the ignition coils probably would've died quick, violent deaths.

It was time for the plugs to be changed, for sure, but does anyone see anything that indicates abnormal combustion?
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Old 11-08-2016, 05:23 PM
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I thought the Series 2 RX-8's come with the NGK Iridium laser tip Leading and Trailing plugs?


NGK states that the Leading and Trailing Iridium plugs are good for 60k to 80k...
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Old 11-08-2016, 05:46 PM
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correction web site states 80k-100k
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Old 11-08-2016, 06:51 PM
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The web site may say that, but the collective practical experience of dozens of owners says an interval of around 20K is appropriate. I change mine every June.

.

Last edited by Steve Dallas; 11-09-2016 at 06:42 PM.
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Old 11-10-2016, 11:41 AM
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Does track driving seem to help or hurt their life? It would seem to help keep them from fouling, but may accelerate wear due to the high rpm spark demands?


at this point I'm not really dailying my RX-8, and just driving it to-and-from events.
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Old 11-10-2016, 05:30 PM
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Originally Posted by hufflepuff View Post
It would seem to help keep them from fouling, but may accelerate wear due to the high rpm spark demands?
Yes :-)

For sure coils (& leads) will need to be replaced earlier (based on track hrs if that is all you are doing).

In a piston engine I'd say the same thing for plugs.

In a rotary, perhaps the accelerated wear balances out the lack of fouling..?
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