This is the #1 reason Subaru turbos die often, second reason is Uppipe cat that breaks up over time. For some reason Subaru thought it was a great idea to put a fine mesh filter into the turbo and AVCS oil feed lines.
AVCS filters are the easiest to get to and check. Some Subaru's will have the mesh filters right before the AVCS, these have a tendency of getting stuck in the AVCS mechanism.
05 LGT bolt didn't seem to have the filter, but my 04 FXT definitely had them and they poped out of the banjo bolts. Dig around in the AVCS oil hole to make sure the filter is not in there, on my FXT, both filters fell out of the banjo bolt and was inside (hard to spot since they are black like the oil).
Turbo Feed/AVCS Feed
This one is the most important one, if this one is clogged it restricts oil flow to the turbo which causes to starve and fail. Most shops will replace the turbo afterwards without fixing the root cause, clogged turbo feed banjo bolt. Because of this most replacement turbos will fail within the next 10k miles.
Remove the bracket that bolts to the up pipe and to the block.
Then you can see the oil feed banjo, use a 17mm ratcheting wrench to make your life easier.
Filter is still in... pull it out and install the bolt without it. The hard lines have a built in restrictor for the turbo.
This filter is definitely clogged, this caused my car's turbo to go out, sadly the previous owner didn't pull it out, thus the replacement turbo might be in a bad shape too.
Driver Side Head AVCS Feed
This one requires the most work to remove, it's best to do it while you are replacing the timing belt and the cam seals.
Here is a pic of how close the Banjo bolt is to the timing cover, there is simply not enough room to remove it on car without damaging the timing cover. If you grind the hump off, you will have more room to get the banjo out.
This plastic cover is in the way and can only be removed with the cam gears removed. You will need to loosen the dip stick tube to get the plastic cover out.
Finally easy access to the bolt
As expected the filter was in place still
And very dirty, if this was on the turbo feed/avcs line the turbo would be dead due to oil starvation.
I removed the whole hard line, notice that the bolt that goes into the AVCS side itself doesn't have a hump. That hump makes it impossible to remove this banjo bolt with the timing cover on.
I'm going to put the humpless bolt on the head, I also shaved one side of the banjo bolt so that I could squeeze it past the timing cover if I ever have to deal with it again. Do yourself a favor and use new seals on the head it self, you can try to reuse the old seals on the AVCS end, they are easy to replace if they leak.
All done and happy!