by bigBADbenny » Tue Nov 22, 2016 11:06 am
How long did the oil light stay on for and did it flicker?
If so that's a sign of a cracked oil pickup.
My car uses heaps of oil, eg 1 litre per 1000klm or less, at 250,000klm: so I've got a spare long motor to go in with various upgrades.
Question is, why? Blame the PO and Subaru, basically.
MY08 was a difficult year for Subaru, the GFC plus the fact that Subaru introduced the G3 Impreza, the car developed from the Gen4 platform, meant that some MY08 Libs were parts bin specials: they have a high failure rate, basically. Regardless, for any Subie:
It all starts with break in, if the car is babied and not broken in properly, the rings will never seat properly.
Then the PO sticks with factory oil and service interval, both of which are optimistic.
Then the oil goes past the rings, oil level gets low, overheats and varnishes the inside of the engine including the oil control rings which become gummed up.
What little oil is there also becomes thinner due to use and overheating leading to either spun bearings or head gasket issues.
This is compounded by the factory fuelling which can lead to fuel starvation on the cylinder closest to the turbo, bye bye ringlands.
That and oil in the inlet from excessive blow-by from the stuffed rings, lowering the fuel's octane rating, leading to detonation.
The heads may also be suspect, eg burnt or bent valves, incorrect clearances or worn valve guides or seals...
Its a viscous cycle, which requires a rebuild or replacement...
So what preventative measures can be taken?
Proper break-in procedure aka hard break-in (google it) on break-in oil, then dino oil, vary revs, limit revs to 5K rpm, limit boost, lotsa vacuum applied initially to seat rings.
Remove, replace or clean any AVCS OCV filters in the block and heads, on postFL these are found deep in the banjo bolt holes at the turbo oil feed (under the turbo inlet pipe on the block), and the heads side feeds on the heads iirc.
Run the serial fuel lines in reverse order (Shadowtuned recommended).
10/40 non eco type synthetic once fully run in.
5k OCI...
Air oil separator or catch cans as per usage scenario.
Killer B oil pickup/baffle/sump as required.
Choose the correct oil pump for your application, eg upgrade only if required for eg dual avcs, or loose tolerances on a built block.
Get it tuned for drivablility and reliability, then economy last. Factory tune favours emissions first, not good for reliability IMHO.
Use a package like BtSsm to monitor your cars health, to log it and take learning views. See my sig links...
Have realistic expectations of your builds potential and do your utmost to research what mods are required to support your goals.
So what to check on teardown?
Heads for clearances etc, OCV filters, varnish etc.
Short block: varnish, ringlands, rings, bearings, cylinder walls, OCV filters, rear AOS cover, main seals on crank.
Sump: shrapnel or glitter in oil, cracked or blocked pickup.
Cut oil filter and inspect internals.
PCV and breather pipes: clogged or stuck?
Last edited by
bigBADbenny on Tue Nov 22, 2016 11:51 am, edited 2 times in total.