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Old 10-03-2011, 12:04 PM   #1
vip997
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Default Spark Plugs

I am looking to buy the best spark plugs i can get. No trying to spend 30 bucks on 1 but you know what i mean, hopefully. Has anyone ever heard of these http://www.ngksparkplugs.com/part_finder/index.asp i found seller selling 4 of these for 50 bucks. I anyone has suggestion on the best spark plugs for my m32008 let me know
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Old 10-03-2011, 07:19 PM   #2
balding geezer
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Default Re: Spark Plugs

NGK Iridium plugs are OEM equipment for our cars. They are about as good as you're going to find. I've used a lot of spark plugs in the last 30 years and NGKs have always been the most reliable for me. Bosch, AC and Motorcraft have also been fine but you cannot go wrong with OEM quality parts, especially when they are a genreally recognized top quality brand.

You can get better prices than what the dealer wants for genuine Mazda parts though. I bought a set of NGK Iridium LTR5IX-11 plugs for my 08 2.0L for less than half the dealer price. Other than branding - these are labelled Iridium IX rather the Laser Iridium and don't have the FoMoCo logo - the only difference between these and the genuine Mazda plugs is the factory pre-set gap. The -11 suffix indicates these are pre-gapped to 1.1 mm/.044", while the OEM ILTR5A-13G-13 plugs are pre-gapped to 1.3 mm/.052". Checking and setting the gaps on a new set of plugs is not as big a deal as removing the engine cover and coil packs to get the old plugs out so I don't see you having a problem.

Obviously you will need to check which are the correct plugs for your car; I don't know off the top of my head if the 2.3 uses different plugs than the 2.0, if that applies. I don't know what a I touring corresponds to; I'm in Canada so we have different trim level labels here - GX and GS are 2.0, and GT is 2.3/2.5.
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Old 10-03-2011, 08:42 PM   #3
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Default Re: Spark Plugs

Yeah i know all about gapping, and stuff. I just didnt know if there are some out there that are better than the plugs that came from the dealer when i got the car new. I heard that copper or some other material of plugs were better.
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Old 10-03-2011, 10:54 PM   #4
balding geezer
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Default Re: Spark Plugs

I've read a few posts here and there about copper core plugs being better in highly boosted engines. Platinum and especially iridium center electrodes are pretty hard, which is why the plugs last so long - the electrodes don't erode. In highly boosted engines you are more likely to see pre-ignition and/or detonation, different phenomena with different causes but the end result is the same - high pressure shock waves in the combustion chamber which can break the harder, but more brittle, and very thin welded tips off the center electrodes on platinum and iridium plugs, resulting in mis-fire. The bigger, more ductile one piece center electrodes on traditional copper core plugs stand up better to this sort of thing.

Of course the electrodes on copper plugs do erode, and do so in boosted engines more quickly than they will in NA engines. But this results in a gradual decline in performance, not a catastrophic (for the spark plug) failure which makes it suddenly stop working altogether. In a stock NA engine either type of plug will work. Copper core plugs are cheaper but you need to replace them more often. I'm sure over the life of the car the total cost is pretty close but with iridiums you don't have to change them every year so that saves some work, even if the long term $$ cost is the same.

I've tried all sorts of weird and wonderful miracle spark plugs in different engines. I've learned it is best to stick with what works. For modified engines you may need to try a colder heat range or, in fairly extreme cases a different type of center electrode, maybe more or less extended, maybe even a recessed "racing" type plug but you've got to make some pretty significant changes in the combustion environment before you need to worry about how tip design come into play. If your stock car has run fine with stock plugs for 3 years I cannot imagine you will see any improvement from switching to a different plug. There may (probably?) will be a noticeable improvement in how the engine starts and runs if you put in some fancy miracle plug but that will simply be a case that any new plug is going to work better than a 3-4 year old worn plug.
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Old 10-03-2011, 11:00 PM   #5
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Default Re: Spark Plugs

If you have less than 90,000 miles on your car, there is no need to replace the spark plugs. The factory Iridiums are good for 90,000 miles.
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Old 10-03-2011, 11:17 PM   #6
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Default Re: Spark Plugs

It is true iridium plugs will last a long time without wearing out. But I've seen too many plugs seized in the cylinder head after 3-4 years to let mileage be the only guide as to when to change them. If you have a 2008, I'd say it is safe to change the plugs now. Even if you pay full dealer price for genuine OEM plugs now it is still cheaper than paying to have a seized or broken plug removed and maybe need to have a heli-coil put in to salvage the cylinder head. And I hate to think what it would cost if the cylinder head needed to be removed to extract a center electrode/insulator that dropped into the cylinder if a seized plug broke off while you were trying to get it out. This pretty rare, but it is the sort of thing which will ruin your day quicker than a dog can lick himself.
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Old 10-04-2011, 12:16 AM   #7
vip997
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Default Re: Spark Plugs

Well i just got a used engine put in my car after hyrdolocking the original. No idea what condition it is like on the inside sinc ei cant open the engine so i want to do everything i can to tune it up. Spark plugs are my first step, then belts and seafoam are next. I have a friend who works at the dealer so he'll do a tune up. I probably will get the NGK ones at 13 a pop
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Old 10-07-2011, 04:00 PM   #8
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Default Re: Spark Plugs

I replaced my spark plugs for the first time in my `04 2.3L about 6 months ago (90-95k miles) with the NGK Iridium IX that others have mentioned. They were ~$12 each at the local AutoZone. I recommend them.
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Old 10-07-2011, 07:58 PM   #9
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Default Re: Spark Plugs

Autolite iridium, good alternitive for sure, about 7 bucks auto parts places.
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Old 10-08-2011, 07:01 AM   #10
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Default Re: Spark Plugs

I bought some at a Mazda dealership in Vegas they weren't too crazy priced either
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