EZ30 oil consumption

[gui67]

Hi,
i have a 2005 Legacy Speb B : EZ30 + 6MT.
it has 375.000km now, I bought it at 210.000km
Since the beginning it was using oil: I needed to add 1l every 5000km, even more when doing long trips. But it did not bother me.
THis summer, I was emptying the coolant reservoir when driving at WOT: there is an exhaust leak through the head gasket.
So I took the engine out opened it.
the intake manifold and runners are full of oil
I did a leak-down test to check the cylinder leakage: it was done cold not warm as prescribed, but the results are very good: between 12 and 17% leakage, (I has the same values on the new S1 I rebuilt a few years ago).
So I removed the heads.
the piston top are full of burnt oil, as the chambers.
but the cylinder walls seem very good: I still see the cross hatched marks.

So I am wondering, what is going on with this oil consumption: It certainly comes from the PCV pipe. (the PCV valve was replaced last year but did not solve the oil consumption problem.
I initially though the problem was the segments which were not tight and build pressure in the crankcase, forcing oil out to the intake.
But the leak-down test seem to indicate the cylinders and segments are still OK.

WOuld you have an idea for the root cause of the oil consumption?

I don't really want to open the engine further.

Should I rebuild it and put a oil catch can between the cover and intake? (it would not solve the root cause but at least limit the pollution of the intake)
Should I purchase an other engine with less miles?
Any other solution?

thanks in advance
Guillaume

[Ric]

I had a very similar model, just a year younger.
(It had done 330,000 km when I sold it 3 years ago.)
Subaru replaced my engine after 25,000 km due to oil consumption issues, and they told me then that the new pistons had the rings at a very slightly different angle which was meant to reduce the amount of oil getting past the rings.
The new engine was certainly much better, but still needed about half a litre every 5000km.
My impression was it used hardly any oil on long trips, the bad consumption was in stop-start traffic where I was doing a lot of engine braking.

[gui67]

For me it is the contrary:
oil consumption is "normal" for every day trips to the office: 20km.

but if I go on holidays, 1000km one way,it will burn more than 1l.

THis weekend I removed the heads and measured the out of round of the cylinders:
top of cylinder 1 has an out of round of 0,07mm on the diameter. which is way above the tolerances.
Top of 5 has 0,05mm
the rest of the cylinders and bottom of cylinder 1 hav between 0 and 0.015, which is OK
I suspect the segments are not tight at TDC for cylinders 1 and 5, buiding exhaust pressure in the case and sending a lot of oil in the PCV system.

Now I am wondering if I should rebuild the engine as is, or purchase an engine with less km, I could have engine between 100000 and 200000km for around 1200€ here in Europe.