Had a slow drip leaving oil on the garage floor. On my last change I
decided to use a copper gasket that was the right size although I had
some hollow steel Subaru washers. I'd bought it years ago for use in
a Honda manual transmission fill bolt (same 18 mm internal as Subaru
bolts).

After removing the underspoiler, it was pretty obvious it was leaking
from the plug/gasket. So with a quick motion, I removed the plug and
covered up the hole with my gloved thumb. Then with my free hand I
removed the copper washer and placed the new steel one on and returned
it and tightened it. I couldn't have lost more than 3 oz of oil -
probably less. It was Mobil 1 5W-30, and I didn't particularly want
to pour the drained oil back, in case there were large metal shavings
in the pan.

I looked at the copper washer, and the crush marks were all around the
circumference except maybe for a 5 mm section that didn't seal (no
mark). I was rather surprised, as I had really cranked it tight.
Anyone ever have a washer not seal even when cranked nice and tight?

y_p_w wrote:

Hi,

Seems odd to me--I've used copper gaskets on a variety of cars,
including my Subie, and never (knock on wood) had one fail to seal. In
fact, back in the days of air cooled VWs, we used to re-use them until
they were nearly paper thin and they'd still seal!

Next time you do an oil change, I wonder if a careful inspection would
reveal an ever so slightly damaged section of either the pan or the bolt
causing your woes?

Rick

Rick Courtright wrote:
Definitely wasn't the bolt. Leak came from the side against
the pan.

I thought it was strange. It should have sealed properly.
I really cranked it tight too. Here's a picture. You can
see where it crushed and where it didn't (at the top).

<http://img58.imageshack.us/img58/3617/washerap6.jpg>

y_p_w wrote:
Could you have cross threaded it?

It does looked as if it had been damaged on installation. Are u using
the subaru seals? The originals are not copper, are they?

Good luck!

Mike Copeland wrote: