Disappearing oil

[revox]

Heya!

 

Well, my 98 OBW (2.5) had the dreaded head gasket issue, so I had everything replaced (including water pump, timing belt, and 1000-or-so seals and gaskets) back in November. The car has been a dream ever since -- except one thing. My oil slowly disappears! I had an oil change in February and when I checked my oil yesterday it was almost at the "low" marker on the stick.

 

My car doesn't leak a drop, it doesn't smoke, there's no oil in the radiator, nothing! So where does my oil go? Should I be worried?

[NoahDL88]

I believe it is in spec according to Subaru if it leaks a Qt or less every 1000 miles, I wouldn't worry, just check every fill up, Most older cars with high mileage leak something, I had an 88 that went through a Qt every 250 miles.

[General chaos]

engines can burn that much and you wotn notice it. or maybe it was an arab recycling team draining a little off in the middle of the night. save the desert. steal back our oil.

Edited April 15, 2011 by General chaos

[unibrook]

My 2001 Forester with 106k on her loses about a quart per 1000 miles. Same way, no drips in driveway, can't see any smoke. But I think if General Chaos is correct, that explains it. That amount of oil can burn off without seeing it in the exhaust. I will go with that.

 

[idosubaru]

Have you gotten under it and check for any signs of wetness or just going by no oil on the ground?

 

Are you absolutely positive it's dry underneath? With only a few months under the belt since all that headgasket work, it might not be dripping down yet. Oil tends to slowly cover things, drip while driving, fill up the crossmember and then eventually starts to drip down on the ground when you park.

 

Otherwise you're probably burning it like they just said. Oil coats the cylinder walls as the piston goes up and down so it's technically impossible not to burn any oil for any car, it's just a matter of how much and usually it's a tiny amount. It's likely getting lost there or the valve stem seals.

 

Did they do a valve job on the heads? Probably not as it's really expensive and annoying on the DOHC's.

 

Have the PCV valve replaced - it's like $7 from Subaru and takes about 20 minutes. It reduces pressures in the crankcase which can cause oil to get pushed around more than necessary where it doesn't need to go.

[wavekayaker]

I had the same problem, but was loosing more like a Qt / 600 miles. It was going into the coolant, but no coolant was going into the oil.

 

Hope it's not that on yours, good luck!

[MilesFox]

I would agree that a car would go through a quart in an oil change cycle. just because the oil was changed, doesnt mean it's full after some miles.

 

The engine will naturally breathe out the oil through the PCV, blowby, and whatever misting and seeping.

[revox]

thanks for all the replies.

 

I've looked under it and everything is bone dry, but I'll check again tomorrow just to be sure. My driveway is cement (almost white) and I'd notice a single drop of oil. There's nothing at all.

 

I'll change the PCV valve very soon.

[subaruplatt]

Not sure if this is a good thing or not but my new -06 doesn't use a drop at 75KM, 6000 KM changes.

I am considering going to a 5000 KM Oil interval as the mobil seems pretty beat up at 6K. There is too much noticeable improvement for me not to diagnose the 6KKM oil as overdue.