[rsrocket1]

I didn't think a 2010 blew head gaskets. My Gen3 2008 had more of the common weeping headgasket which simply weeped oil out the side and did not compromise the combustion seal.

Your problem might be more of a cooling system problem than a headgasket. Are you sure the fans are running at the right temperatures and right speed conditions and A/C settings?

You might want to get a combustion chemical test kit to check for exhaust gases in the coolant.

 

[idosubaru]

Leave the car running and look into the overflow tank and it's bubbling like a jacuzzi.

That isn't a comfirmed headgasket, granted we're assuming some things based on your description:

1. Overheating. Boiling and bubbles are not the same thing and require a little discernment to differentiate.
Overheating has many causes.
need to check the cooling fans, for air in the system, thermostat (OEM only), and for any small leaks, and coolant loss over time that isn't from boiling out.

2. If it is bubbles, and not boiling, then it's nearly guaranteed to be headgaskets.

 

[johnre]

I didn't think a 2010 blew head gaskets.

The EJ253 engine was still used through 2011 model year, and are in theory still vulnerable. In practice, the failure incidence rates have been much lower on this engine starting with the 2009 model year, per non-scientific anecdotal information in our HG failure log:

http://www.subaruoutback.org/forums...83-hg-failure-log-no-discussion-log-only.html

 

[Honda.Fan69]

High temperature idiot light only came on once (flashing) and was not on when tank was bubbling. When the overflow tank was bubbling there was no steam like it was boiling but coolant in tank was highly aerated almost cloudy and level was so high in tank it was squirting out the overflow hole at the top. I don't have an infrared temp gun or a thermometer that I can measure the coolant temp with.

Don't remember if the fans were running or not. I know they come on when the AC is turned on but since it didn't appear or indicate it was overheating I didn't pay attention to the fans.

I'll look for one of those kits to test the coolant.

I'll also add that lately i've been adding a quart of oil every 1,200 miles between changes and plugs were a nice clean tan when I changed them. Which was when I did the timing belt, water pump, and T-stat. Two plug wires on driver side had oil on them so think valve cover gaskets are leaking a bit on that side too.

 

[Honda.Fan69]

Trying to attach video

 

[RoughDiamond]

Welcome to the club. While the internal gasket failures (like you are experiencing) are exceedingly rare, it does happen. I did a 2011 Legacy a few months ago with the exact same issues and with the owner trying the same remedies.

30k miles after the HG swap, still no issues. The other tell-tale is the fluctuating coolant level in the overflow bottle. If it doesn't return to the same level (from cold to cold), you typically have a problem.