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2006 Forester
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662 Posts
Discussion Starter #1
I replaced my spark plugs today with OEM Subaru NGK plugs (part #22401AA65A) and noticed there wasn't anti-sieze dope on the threads. Well I lightly applied some to each new plug before replacement. Now, in retrospect, I'm wondering if I should've left the threads clean since they came that way?!?!

Do our spark plugs need anti-sieze?
 

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Administrator
2007 Forester Sports XT 4EAT
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The answer is on this thread. Start at my post & continue down thru the thread. :wink:

Bobby...

My MODding Journal
 

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TANSTAAFL
2010 2.5X Premium AFF 4EAT
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472 Posts
Excellent link, thanks.
 

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2019 Crosstrek 2018 XT
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14,503 Posts
Yea..as pointed out the torque for the NA should be about 10 ft. lbs. with antisieze.

If the wrench " clicked off" when you were done..you should be O.K.
 

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yep, always use anti-seize paste on spark plug threads, otherwise you risk breaking the head/tip of the spark plug off into your cylinder = not fun to remove.
 

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2019 Crosstrek 2018 XT
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yep, always use anti-seize paste on spark plug threads, otherwise you risk breaking the head/tip of the spark plug off into your cylinder = not fun to remove.
That will only happen iv you get the wrench on there crooked. (In my experience anyway)
 

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2008 Forester X Premium 5MT
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8,071 Posts
After years of wrenching on motorcycles with aluminum heads, I wouldn't put a spark plug into one with out anti-seize.
 

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05 FXT
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Didn't read the thread, but 100% agree w/ flstffxe.

Steel threaded into aluminum not good. If you change pretty regularly, probably not a problem. If you get water in there and they sit, you're not getting them back out. Don't believe me, go to a u-pull it junkyard and try pulling the plugs out of a head that's been sitting there for a while.
 

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2000 Forester L
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315 Posts
I always use anti seize on everything from my old air cooled VW to V8s, Tbird SC, VW VR6, etc. I haven't done any Subarus yet.
 

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2008 Forester X Premium 5MT
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Didn't read the thread, but 100% agree w/ flstffxe.

Steel threaded into aluminum not good. .........Don't believe me, go to a u-pull it junkyard and try pulling the plugs out of a head that's been sitting there for a while.

I helped work on a 2.5L last year doing HGs. It turned into the nightmare from hell. Car had great records of most all of the repairs for the past ~220,xxx miles, only record of the plugs being done was at 100K when the HG were done last.

When the other guy pulled out the first plug it took the threads in the heads out with the plug. The second plug broke off below the hex leaving the threads in the head the 3rd came out easy as pie and the fourth broke just like the second.

Seeing as we had to repair one hole already and remove 2 other plugs from the heads we chose to set it up in a mill at a friends shop where we used the clean plug hole and a shaft threaded into it to align the head on the table. Milled out the two broken plugs, threaded all 4 holes to fit thread inserts and installed 4 Full-Torque spark plug repair thread inserts.

All in all if he would of had to pay for those repairs I have seen similar repairs run around $2500-3000, all to replace spark plugs. In essence on a subaru it is the same as doing HG plus the additional cost of repairing the spark plug holes. His only saving grace was the heads were already coming off for the HGs and we have the connections to make it happen with basically just the additional cost of the inserts.

Moral, use anti seize and change the plugs at least as often as scheduled and don't over torque them.

As a preference I use copper based anti-seize for spark plugs and other electrical sensors(O2 ect) and high heat items, aluminum based products for every thing else not stainless steel(fasteners) those get nickle based products.

Copper based

Aluminum based

Nickle based
 

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05 FXT Broken 5-speed
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239 Posts
Anti-seize is your friend for every exhaust bolt/nut on your Subaru. Always put some on new spark plugs. Also, I put alittle bit on the 12mm bolt that secures the coil pack. Next time, it makes it SOOO much easier. Basically, you can break it loose, and then turn it out by your finger tips.
Absubtle
CO
 

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2005 XS
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166 Posts
Back in the day when I was riding Hondas (CB-350 Four and later a CB-750F Super Sport), I never heard of anti-sieze and thus never used it. Since I had never had problems getting spark plugs out, I never even thought about it.

However, the one item that kept bugging me was that I was going to cross thread the plug as I screwed it in. Many, many years ago, I had done this with my Dad's "Lawn Boy" lawn mower. Back to the motorcycles: I used a short section of rubber hose, (fuel hose, I think) and slipped it over the end of the spark plug and turned the plug into the threads by twisting the fuel hose. The idea being the fuel hose would slip and not turn the spark plug if I had it going in with crossed threads. Now, I can't say for sure if this REALLY worked, but I've never cross threaded a spark plug when using the fuel hose.

By the way, the four or five inches of fuel line made a dandy extension for getting the plugs into the heads of the Honda motorcycles.

Ray Lovinggood
Carrboro, North Carolina, USA
 

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2019 Crosstrek 2018 XT
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Back in the day
My experiences are pretty similar. I used to use a small bit of oil and never had a problem. And I always thread in the plug by hand..all the way..only the extension/socket..no wrench. And I always then back it out a turn or two and re do it just to be sure.

And I always remove the plug very slowly on a cold engine. If its tight run it back in a turn or so..very slowly. You will not strip a dry plug if you are careful. But I do use a very small amount of anti-seize.

Yea it was easy to strip holes on those old Brig's heads. :D
 

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2007 Forester Sports XT 4EAT
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I always use a touch of Pematex anti-seize! :smile:

The first car I wrenched on was my 64 VW bug. Talk about spark plugs messing up the heads! The spark plug thread length was shorter & the aluminum heads seemed extra soft so stripping out the threads was way too easy to do! After that happened to me, I had Heli-Coils installed in both heads! :wink:

Bobby...

My MODding Journal
 

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2005 XS
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adc,

The "Lawn Boy" mower didn' have a Briggs & Stratton. They had two-stroke engines and, at that time, were owned by OMC (Outboard Marine Corporation), the same people who made Evenrude and Johnson boat motors.

With two-stroke lawn mowers, and two-stroke motorcycles, and two-stroke model airplane engines (Cox 0.020, 0.049; OS Max 0.40), I've inhaled enough gas and oil to keep me lubricated for the rest of my life... Oh yea, I spent a few hours in "East Berlin" back in the mid 1980's and with the Trabbies running around, I got another dose of the blue cloud stuff...

Ray
 

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2016 Outback and WRX CVT
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Anyone else here use anti-seize on the mating surfaces between the hubs and wheels?

Makes the seasonal tire rotations/changes so much easier!
 

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I thought you were supposed to use nickel based anti-seize when installing into aluminum heads... something about copper based anti-seize reacting with the aluminum or is this just a legend?
 

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2008 Forester X Premium 5MT
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I thought you were supposed to use nickel based anti-seize when installing into aluminum heads... something about copper based anti-seize reacting with the aluminum or is this just a legend?
From Permatex for the copper based:
Suggested Applications: Spark plug threads installed in aluminum, exhaust manifold bolts, engine bolts, oxygen sensors, knock sensors, thermostat housing bolts, fuel filter fittings, and battery cable connections
However there is a galvanic reaction aluminum and copper have when they are in contact with the same conductive fluid(electrolyte), the aluminum being the one that corrodes. I believe the reason Permatex suggests the copper based is that it has less of a galling effect then the nickle with the aluminum And that the area that the copper based anti-seize is being applied to(threads below the sealing surface of the plug) is a dry area with no fluid contact to promote the galvanic reaction.

Now stop making me think back to high school chemistry:biggrin:
 
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