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Old 10-02-2012, 03:23 PM   #1
SubieNut09
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Default Spark Plugs

Hi, I have an 09 Impreza 2.5 non turbo coming up on 31,000miles and want to replace my spark plugs, I was thinking of going with the NGK Iridium, or the Bosch Iridium, are these ok to use or should I just use the stock plugs? I figure I could get more mileage on these plugs. Which one do you recommend and do I need to use anti-seize.
Thanks in advance.
Bob.
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Old 10-02-2012, 03:40 PM   #2
JohnM10
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I believe NGK is the OEM brand so they are a good choice and skip the anti-sieze as it is not needed.
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Old 10-02-2012, 03:58 PM   #3
SubieNut09
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Thanks John.
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Old 10-02-2012, 04:04 PM   #4
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Quote:
Originally Posted by JohnM10
I believe NGK is the OEM brand so they are a good choice and skip the anti-sieze as it is not needed.
Steel plugs in aluminum heads plus lots of heat and you say anti seize its not necessary? Sounds like a recipe for disaster.

Anti seize certainly will not hurt as long as you keep it off the electrodes. Some dielectric grease in the boot that goes over the plug is good insurance against moisture/corrosion and arcing, too.
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Old 10-02-2012, 05:29 PM   #5
Counterfit
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^ This

NGK FR5AP-10 is the part you want. Subaru says it's the -11, which is too large of a gap, according to the FSM.
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Old 10-02-2012, 10:10 PM   #6
alt14
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I think the recommend gap is .006, I can't remember off the top of my head but I have a service manual somewhere is you need the specs on it
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Old 10-02-2012, 10:15 PM   #7
Counterfit
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That sounds awfully large small.

Edit:
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Old 10-03-2012, 01:40 AM   #8
Bababou
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Ive run both and the NGK has been better for me.
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Old 10-03-2012, 11:01 AM   #9
JohnM10
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Old 10-03-2012, 03:51 PM   #10
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Thanks to everyone for all the help.
Bob.
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Old 10-03-2012, 04:44 PM   #11
alt14
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Quote:
Originally Posted by Counterfit
That sounds awfully large small.

Edit:
I think I meant .6 lol I have to take a look
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Old 10-03-2012, 04:56 PM   #12
Counterfit
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Then I was right the first time, that's huge! You probably mean 0.06, which is still big, but not ridiculously so.
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Old 10-03-2012, 06:02 PM   #13
alt14
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I have no idea why I thought it was 6, I just looked it up, .039-.043 at 15.2ft-lb torque
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Old 10-03-2012, 06:57 PM   #14
Counterfit
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Then you want the FR5AP-10
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Old 10-03-2012, 10:17 PM   #15
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Quote:
Originally Posted by Counterfit View Post
^ This

NGK FR5AP-10 is the part you want. Subaru says it's the -11, which is too large of a gap, according to the FSM.
This.
I actually emailed Subaru Canada about why the Owners Manual called for the -11 plug when it's already at the high end of the range (and will generally grow with use) according to the FSM. As expected, they didn't really answer the question, just reiterated the FSM gap range

Saying all this, I still use the -11 plugs (dealer servicing to keep my warranty) and haven't seen any issues or excessive gaps at the end of their service life. Of course, a larger gap will be more of an issue if your electrical system is not up to snuff....
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