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2018 3.6 Outback Limited, 2013 2.5 Legacy Premium
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Discussion Starter #1
I just replaced all four of my spark plugs with Subaru OEM ones on my 2011 at 76000 miles.

I will say the job was relatively easy and it was nice not to have to deal with wires, instead only unscrewing the coilpack. With all the right tools to get it done, I'd have no qualms over doing this again in the future.

BUT, once I pulled the plugs and coilpacks, I did notice there was a smudge of oil on the packs and the plugs looked completely clean. I asked a friend of mine if he would be worried about the oil smudge and we both dismissed it as anything more than just a slight seal leak (see pics of the plugs and the smudge).

Just thought I'd inquire here to get a quick second opinion. Some backgorund: I've been using Mobil1 Full synthetic oil, doing all my own changes, and have seen some oil burning off (no spots on driveway) and add a quart after about 5-6k miles. I usually run about 7500-8500 miles between changes. Once I got everything put back together, the car started right up and has been running smoothly since (about a week now).

Thanks in advance!
 

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I simply cannot abide useless people.
2006 2.5i and 2002 3.0 wagons.
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12,306 Posts
That might be the very start of the valve cover gaskets starting to weep. Nothing to worry about now. Check the plugs at your next change and see how it is.

Kaylee needed VCG at 101K, Mal at 90K. Seems to be a thing.
 

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2012 Outback Ltd 3.6r
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487 Posts
Looks like the plug o-ring seals are seeping a bit. Once it starts dripping onto the driveway, it will be time to replace the gaskets and plug seals. I think it happens more with age than mileage, had the same thing with my '02 Envoy, and my sister's '03 Forester after several years.

Be glad it's a 2.5, a whole lot easier to replace the plugs and gaskets than the 3.6/3.0 H6 models. I'm not looking forward to my plug change with my big hands. - Dealer claims they loosen the engine mounts on the H6 and raise the engine enough to gain clearance. (They also get something close to $500 to do the plug swap on an H6).

I'll talk with my brother and see if I can use his lift when the time comes.
 

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2011 Subaru Outback 2.5i Limited
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181 Posts
I just did the plugs on a new-to-me '11 and saw very familiar markings. I also saw some corrosion down inside where the plug sits like water was in there for a while (driver side front plug was the worst).

Fortunately I did have new coil seals to put on but I wasn't sure what to make of the corrosion and stains on the coils.
 

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2019 Subaru Forester Premium, Crystal Black Silica, Pkg 15
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Does being a little late with the plug change contribute to the problem? I believe the manual suggests the plugs around 60k. My wife's 09 Legacy used to need them every 30k if memory serves, and they looked pretty beat up every change. I chalked it up to the design of the Boxer and moved on.

I haven't done my own change on my 2.5 Outback, and probably won't since I'll probably have the 3.6 before they're due again - and I've heard they're a real ******* to change over in the 3.6.
 

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2011 Subaru Outback 2.5i Limited
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I believe the interval for iridiums is typically 100k but many people wouldn't recommend actually going that long.

I don't know why everyone complains about changing these plugs, I thought mine were like a 1/10 on difficulty scale. Maybe older gens were harder?
 

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2019 Subaru Forester Premium, Crystal Black Silica, Pkg 15
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I believe the interval for iridiums is typically 100k but many people wouldn't recommend actually going that long.

I don't know why everyone complains about changing these plugs, I thought mine were like a 1/10 on difficulty scale. Maybe older gens were harder?
The H6 is a lot bigger, so there's less room to work with. The H4 has a lot of room in the engine bay and isn't so bad, just a little prep moving the air intake etc getting to the front pass side.

The 2018's are still using iridium tipped ones, too, with the 60k interval... The ones on the Legacy were NGK Copper Core with Platinum Tips, and needed a 30k interval per the manual. Again, this was an older gen Legacy, and the Gen5 Leg (2010+) and Gen4 Outback (2010+) have NGK Copper Core with Iridium Tips, and apparently these make it to a 60k interval.

With the boxer design the plugs seem to take more of a beating because they are horizontal, gravity helps the inline and V-style engines because it keeps the oil down. Perhaps the oil was leading to issues with corrosion on the Gen4 Leg/Gen3 OB. I'm sure there was a method to their madness.

They also suggest oil changes at 3000 severe/6000 standard now instead of the old 3750/7500. Makes me wonder if some type of problems popped up that might have been mitigated or avoided with the extra interval.
 

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2011 Subaru Outback 2.5i Limited
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The H6 is a lot bigger, so there's less room to work with. The H4 has a lot of room in the engine bay and isn't so bad, just a little prep moving the air intake etc getting to the front pass side.

The 2018's are still using iridium tipped ones, too, with the 60k interval... The ones on the Legacy were NGK Copper Core with Platinum Tips, and needed a 30k interval per the manual. Again, this was an older gen Legacy, and the Gen5 Leg (2010+) and Gen4 Outback (2010+) have NGK Copper Core with Iridium Tips, and apparently these make it to a 60k interval.

With the boxer design the plugs seem to take more of a beating because they are horizontal, gravity helps the inline and V-style engines because it keeps the oil down. Perhaps the oil was leading to issues with corrosion on the Gen4 Leg/Gen3 OB. I'm sure there was a method to their madness.

They also suggest oil changes at 3000 severe/6000 standard now instead of the old 3750/7500. Makes me wonder if some type of problems popped up that might have been mitigated or avoided with the extra interval.
I'd believe the 3.6 is more difficult. Most of the rest of your post seems in line with my knowledge base or at least logical :)
 

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2010 Subaru Outback 2.5 Limited
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40 Posts
I have a 2010 2.5 myself and changing the VCG and tube seals is a real pain in the butt so it's likely similar with the 2011. You have to lift the engine a bit by unbolting the engine mounts and jacking the engine up by the oil pan (with a block of wood). From what I'm told the 3.6 is a job for a shop so luckily you have a 2.5. :D
 

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2010 Subaru Outback 2.5 Limited
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I don't know why everyone complains about changing these plugs, I thought mine were like a 1/10 on difficulty scale. Maybe older gens were harder?
My 2001 Legacy was easy and a quick job. My current 2010 Outback, pain in the butt as far as I'm concerned.

Even the VCG and tube seals were super easy with the 2001.

Man, I miss that 2001 beauty.
 

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2018 3.6 Outback Limited, 2013 2.5 Legacy Premium
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Discussion Starter #12
Thanks for the replies everyone! Got busy and forgot to come check back in on this.

Comparatively to what some of you have reported back on your coils and plugs, I'll consider how mine looks just plain near-perfect! I have no clue what's involved with changing those seals at my next plug change but hopefully it's as easy as doing teh plugs themselves which, as I believe I mentioned, wasn't really hard at all on this engine. Kind of glad I don't have the 3.6 now!

I have been running full synthetic since about 10k miles at an interval of about 7500 miles +/- 1k miles. Not sure if that has to do with my seepage or not. I knew the plug change interval was around 60k but have hit a sort of gas mileage hit and was hoping that maybe it was older plugs causing it; hasn't seemed to improve at all since the change though (even with all new filters, oil, etc that I changed when I did the plugs).
 

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2019 Subaru Forester Premium, Crystal Black Silica, Pkg 15
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Try cleaning your maf sensor. There?s a special cleaner by CRC that i used. It is part of my routine oil change maintenance now and takes about 5 minutes.
 

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2018 3.6 Outback Limited, 2013 2.5 Legacy Premium
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Discussion Starter #14
Try cleaning your maf sensor. There?s a special cleaner by CRC that i used. It is part of my routine oil change maintenance now and takes about 5 minutes.
Hmm, never thought about this! I'll pick up a can and give it a try! Thanks :)
 

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2014 OBW Premium (Ice Silver Metalic)
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I've also recently noted a hit in my fuel economy on my '14 Outback. At first I was thinking I was due for plug replacement, but being as it's mid-November I wonder if the change-over to winter blend gasoline might also be a contributing factor. Never the less, I know that spark plugs are in order.
 
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