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My wife and I recently bought a 2011 Legacy as I thought the HG issue was resolved in 2005 but it really hasn't been. However starting in 2010 Legacy/Outbacks are running the MLS gaskets from the 07+ STI. Because of coolant flow hot spots the common feeling is the cylinder head is also a semi closed deck, but no one can confirm until one is torn apart. Turbos in general have had better realibility in the HG arena so if this gasket can handle 300 HP I feel pretty good having it hold onto my 170 hp. I'll do my mainteance on schedule and even though the manual says the new coolant is good until 135k miles...no thanks. I'll swap it at 50k then with the belt at 105k. Subaru still calls for the conditioner to be added but that doesn't surprise me at all.

I visually confirmed this on my car as well. You can see that the gasket is bright metal and has multiple layers, there is also a hump section near the front of the block that exactly matches the STI's gaskets.

I love the car and my sister lovers her 2011 Outback! If you're in the market for one I can't recommend them enough.
 

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2004 Toyota Sienna, miss my eyesight. Life moves on.
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Here is the link to a Seattle WA automotive technicians website that will explain almost everything to you. I'm specifically including the link about the 2010+ Outback Legacys but you can read all his other blogs and articles while you're there.

Subaru Changed Their Head Gasket For The 2010 2.5L - Seattle Subaru Repair

Here is a video explanation of the 2010 as well.


He gives full explanations on what is causing the problem and he even helped give a couple design queues on the MLS gasket they use for older models that has yet to fail on him. The Turbos and H6's have been using MLS gaskets for years with much lower failure ratios. So having a MLS or "beefy" gasket is the first plus the semi closed deck keeps the block from flexing as much which rubs the gaskets. Metal moves and thats just how it is but a semi closed deck block moves less so there is our second plus.

I never book marked the PDF I found that had the full Subaru PNs but the new gaskets end in 670 and the old ones were 633. The current turbo gaskets are now 770. I found a comment somewhere where this was acknowledged but no one new what the 770 update is.

I'm a backyard mechanic but not a certified one. I hope I've helped point others in the right direction. If you have a mechanical question about this search the blogs on all wheel drives website and if you don't see your answer just ask him. Hes a really nice guy who knows his stuff. Hopefully this will put current owners with concerns at ease, like myself, and help prospective buyers buy with confidence.
 

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2004 Toyota Sienna, miss my eyesight. Life moves on.
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Its really hard to verify everything right now with these models being so new. One thing I did was go to rockauto's website and compare their PN's through the years. This is how I was able to link 07+ STI's to 2010+ Outbacks, that and the mysterious Subaru PDF I can't find!

Go to a lot with a skinny screwdriver, and ask to pop the hood on a new one. Look at the front of the head (radiator side) and you'll see parts where the gasket pops up a little and it will be shiny metal. Then you can lightly flick the top of the gasket with your screwdriver and it will separate into 3 or 4 pieces. In fact you can see the mutliple layers without even touching it. This will ensure for anyone in person that its a MLS gasket vs the old single layer 633 gasket.

This isn't a gaurentee that we'll never see a head gasket failure on these models. From my research on the H6's they usually either don't fail or fail north of 150K. I'm perfectly fine resealing an engine after 150k for the AWD, safety, and to keep the car if I still like it. Its the sub 150k mileage failures that suck. Bad coolant and bad oil will eat any gasekt and with the boxer motor the gaskets are simply subject to this more than an inline or V motor. This is why I'm NOT waiting until 7500 miles to change my oil. In the winter I'll follow the severe schedule of 3750 and summer I'll do 5000 oil change intervals. I'm going to use full synthetic as well. For the coolant I'll drain the radiotor and top off every 50k with the 100k intervals seeing a new timing belt. Also don't let your battery get corroded, keep it clean!
 

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2004 Toyota Sienna, miss my eyesight. Life moves on.
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I completely agree that all signs point to a semi closed deck. Now some people online have claimed that this gasket can be used on an open deck for a rebuild but I don't think thats a good idea and I can't imagine an OEM doing that. Hot coolant banging directly against that closed port would in my mind create premature wear. I don't see SOA directly admitting to the change either. If they ever said anything they would probably claim it was cheaper to manufacturer all 2.5's to the same specs.

The sad part about all of this is all of their cars would be closed deck if they weren't trying to save a few buck on aluminum per engine. I wonder how much they've saved with open deck designs vs how much HG failures have cost them direct and indirect over time.
 
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