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.

[gui67]

I decided to replace the engine as the current one is out of spec.
The engines I can find are post facelift, or from Tribeca: 2007 or 2009. So I think these will not have the same camshaft as the one I currently have. (U30 vs Z30)

I am wondering if I should switch the camshaft and put the "old" ones in the new engine,
Or keep the new ones. Is there an impact on the tune? Do you know if ve maps for example are different? (I have tactrix openport to do that if needed)
Or is there a gain to use he biggest cams from one set and the other? for a NA setup.

Do you have any previous experience of this upgrade: benefits or difficulties (tuning) linked to the change?