A leak at the rear main would present itself between the engine and transmission/differential seam. The 2000 (second generation) Outback is known to have valve cover gasket leaks. If you have oil on your spark plugs it could be from a bad valve cover gasket, so take a look there. An oil leak is hard to trace to its exact cause because a little bit of oil, when blown back towards the exhaust when driving, can look like a lot of oil from somewhere else. In which case a rear main seal might cause oil to be blown back as far as your cats.

If it is the rear main then you have about a $4 part with about $400 worth of work to get to it. Check the valve cover gaskets first. Fingers crossed.

 

If it were the rear main, would I see oil coming from the seam where the transmission and engine mate together? I don't see any leak there. I didn't think about the oil being blown back from wind. There is no oil anywhere near the cats.

 

Rear separator plate would be my guess.

 

^+1

 

Subaru rear mains almost never leak. if they do it's often a recently replaced one that leaks, not the originals.

almost ever fluid leak in the car angles centrally and gets blown back to that jack plate at the rear of the engine. so they're usually hard to immediately diagnose.

what fluid is loosing amounts? that will tell you what's leaking.
ATF?
power steering?
engine oil?

 

I know for sure that it is engine oil, just trying to figure out where it is coming from.

 

great, look up and forwards. the source of the leak is not generally where you see the oil under the car. that's just where it ends up based on gravity, geometry of the engine bay/crossmember, and blow back.

the furthest forward and highest signs of oil are what you want to note - not the lowest points. every leak ends up low.

 

The car is due for spark plugs and wires, I'll be changing them soon, so I will be able to tell if the leak is coming from the valve cover gaskets, although I'm pretty sure it isn't because when I was under it a few days ago everything around the heads and covers looked dry. The timing belt cover also looked dry except a little bit of oil below the fill spout, but I'm pretty sure this is just from spills while filling, but I'll take the cover off the timing belt to be sure. Any other places to look? If it is the separator plate or rear main is the cause, how urgent is this for repair? This is a manual transmission BTW. It isn't a huge leak at this point. We are planning a 1500 mile trip next month, and we had planned to take this car as it gets better gas mileage than our other.

 

Don't forget that when you drive, the leaking oil is forced by air towards the end of the engine and that is, where it drips. So, it may not be leaking in the back after all...

The best is to hoist it up, dry the area and see, where it leaks from. Many cities in the U.S. now have places that rent you a hoist and work on your car yourself... not sure if you live in such city or if you have one near by...

 

Don't forget that when you drive, the leaking oil is forced by air towards the end of the engine and that is, where it drips.

The best is to hoist it up, dry the area and see, where it leaks from. Many cities in the U.S. now have places that rent you a hoist and work on your car yourself... not sure if you live in such city or if you have one near by...

I'm pretty lucky as I have a friend with a heated and air conditioned shop with a lift. :grin2:

Oh and beer on tap.

 

I've had an oil leak in my 2009 Forester 2.5L with 114,000 miles.Took it into a local mechanic to have it diagnosed and they came back with head gasket and right valve cover gasket as well as _rear main_. From an earlier post stating that the rear mains "almost never leak", I'm wondering if it's a misdiagnosis?

 

my EJ251 (similar to your EJ253).

leaked: rear main, cam, and finally a drivers side head gasket. one at a time in short order.
last one was the drivers side head gasket.

2009 /2010 foresters were made with single layer steel headgaskets,

and a reason to change all the oil seals when the work is done. when the engine is out for as part of a typical head gasket job.
(with turbo head gaskets = multilayer steel).

 

If you have access to a lift, try using UV dye. If your friend has a lift, i'm guessing he has an engine hoist and stand. The car is 18 years old, if it is the rear main, and you pull the engine, consider replacing head gaskets.