Oil found in spark plug cylinders!!

[striktlysubie]

2015 WRX - Car is still at the tuners getting numerous repairs done, and when removing the spark plugs and coils for a planned 90k miles replacement, oil was found in all 4 plug cylinders!!!! Has anyone else experienced this, and is it common? Also, any expected short or long-term damage? It could explain why I've fouled out four O2 sensors so far. We are now getting all the spark plug coil rubber gaskets replaced, as well as the valve cover gaskets (which were corroded). Not sure yet if this could have also been causing some or all of my rough driving and CEL issues (i.e. knock and A/F sensor ratio imbalance). Open to all feedback!

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[Charlie-III]

The spark plug tube seals are leaking. Replace those along with the valve cover gaskets. Common issue on many brand cars. Besides being messy, not much of an issue.

[striktlysubie]

Originally Posted by Charlie-III

The spark plug tube seals are leaking. Replace those along with the valve cover gaskets. Common issue on many brand cars. Besides being messy, not much of an issue.

Thanks for the info. We are indeed replacing the tube seals and the valve cover gaskets. I'm not thrilled that these are all rubber parts, but that's what was ordered from Subaru. Then we will toss in the new spark plugs and coil packs, and re-tune for the new FMIC.
Also has me wondering now what other "common" parts failures are expected on the car (at about 90k miles and approaching 10 years old). ????

[Charlie-III]

I would NOT consider these "parts failures", these are age/mileage related wear items. All cars with spark plug tubes leak at some point since the general design is similar. Does not matter country of mfr, brand, etc.

Reading the maintenance schedule in the owners manual gives a basic idea. It will list time/miles to inspect or replace lot of items.

[striktlysubie]

Originally Posted by Charlie-III

I would NOT consider these "parts failures", these are age/mileage related wear items. All cars with spark plug tubes leak at some point since the general design is similar. Does not matter country of mfr, brand, etc.

Reading the maintenance schedule in the owners manual gives a basic idea. It will list time/miles to inspect or replace lot of items.

Thank you for this info also. Just still stinks considering I've owned a few Hondas a lot longer than this car, and have never had this issue. But maybe, Subaru + turbo = easier wear and tear. The car is still being repaired as of today.

[Elbert Bass]

Yup just Subaru specific maintenance.

Your honda spark plugs install vertically. Most the Honda tube seals see is oil mist.
Subaru spark plugs install horizontally. Subaru tube seals get oil splash from rockers and cam lobes.

It's not a design flaw, it's just the difference in maintenance required between inline/V design engines and horizontally opposed engines.

[striktlysubie]

Originally Posted by Elbert Bass

Yup just Subaru specific maintenance.

Your honda spark plugs install vertically. Most the Honda tube seals see is oil mist.
Subaru spark plugs install horizontally. Subaru tube seals get oil splash from rockers and cam lobes.

It's not a design flaw, it's just the difference in maintenance required between inline/V design engines and horizontally opposed engines.

Thank you for the good education here. The car still has other problems (separate thread), but the valve cover gaskets, spark plugs, and coil packs were all replaced a few weeks back, so the oil leak issues should be resolved. Fingers crossed.