Oil Thirsty Engine - Causes?

[mikec]

Hey Everyone,

This is somewhat related to other posts, but because I can't figure out exactly why the engine is consuming oil, I wanted to start a new thread. First, what I've noticed, then the questions.

Just recently (the last month or so), the engine has started consuming oil at a fairly high rate. Based on the reading I took today, its about a quart per tank of gas (unless the dipstick is totally off). A tank of gas lately is mostly highway driving, with a bit of city driving.

I do know since I bought the car that there has been oil present on the front passenger side spark plug threads. After looking today, there are no apparent signs of oil leaks around the valve covers, oil pan, etc. There's no signs of burning oil in the exhaust when I start the car, or from what I've noticed when pulling away from a stop. Also, there's nothing on the ground where I've parked the car.

The only bad thing I've done to the engine was running it up to 5000 RPM or so not too long after starting it, with the car in Park (therefore no load on the engine). Stupid, I know... I looked back after letting it come back to idle, and discovered a huge cloud of white smoke. Otherwise, I'm fairly gentle with it, but do occasionally run it to redline on the highway after its warm. But this seems to be about when the oil problem started.

So... Does anyone know what might be causing the oil consumption? My brother (by no means an expert), thinks piston rings. But someone had assured me in another thread that they've never seen the rings go bad. Could the stupid trip to 5000 when cold have damaged them? I don't have the skills to start pulling things apart, and I don't think its something I can easily access. If it helps, I'm currently running Quakerstate 5W30 with a Subaru oil filter. I'm also about 500 km from an oil change.

I don't really want to go to the dealer, because I'm worried the diagnosis alone will be costly, but I'm not sure I've got any other option.

[entirelyturbo]

You're probably not burning any, but most likely leaking a little from all your seals. I have replaced:

Valve cover gaskets/grommets
Right rear cam seal
Change crush washer on drain plug every time
Front crank seal

And guess what??? I'm still leaking!!! But I'm not burning a drop! And I'm not leaving any on the ground.

Yes our dipsticks are horribly inaccurate, find my post about that very subject...

FWIW, no older Subaru is ever 100% oil tight, ever! If you really want it to be perfect, just pull the motor and replace every last God-forsaken seal in the entire engine, and that's still not a guaranatee...

Try a slightly thicker oil, I'm using 10W40 right now, and I haven't seen gross oil losses yet.

And yeah, since our engines are aluminum, you gotta go easy on them when they're cold. But one little 5000-rpm incident shouldn't do any internal damage.

Good Luck!

[mikec]

Hmm... warmer weather over the last month... seals that are probably 12 years old... I suppose its possible that the thinner oil is just sneaking out.

I guess I'll try a thicker oil with this change, and see if that helps at all.

Anybody have any luck with any of those "higher mileage" fomulations? Does anyone think its worth trying?

If anyone still thinks its a sign of something I should be looking into, please let me know. Gas prices are bad enough without having to put in a quart of oil with every fillup!

[Legacy777]

The revving to 5000 thing when cold will not affect anything assuming your engine & oil circulation is functioning properly.

With that aside, any blue smoke out the exhaust is in one way getting into the combustion chamber. The two most common ways are by the piston rings or through the valve seals.

First thing I would do is compression test/leak down test of the engine. If you find that during the leak down test you are slowly loosing pressure, squirt some oil in the spark plug hole. Then do the leak down test again. If results improve, you can pretty safely say that "at least" the piston rings are worn..."but may not be limited to just rings"

If you do oil trick and things don't improve.....it's probably the valve seals.

If you find it to be more the valve seals.....I can probably see having the heads removed and redone. At that time you could check out the condition of the cylinders and see if there is any obvious problems.

If it is more in the piston rings.......I'd probably suggest trying to find a used low miles motor......unless you got the money for a rebuild.

Just a final wrap up......oil has to go somewhere.....if you are not leaking any major oil puddles you are most likely burning it. Small oil seapage around the seals is somewhat normal....but it's no way going to leak close to a quart and you not be able to see it.

You could try a heavier weight oil as a temp bandaid....have no idea how effective it will be though.

[IggDawg]

My engine doesn't burn a drop. it doesn't "leak oil" per se at all either.

HOWEVER it DOES secreat a special "anti-corrosion compound" which coats the underside of the engine to prevent oxidation of the engine components .

[mikec]

Josh - Hrm.... I was expecting to hear something bad, but somehow it still hurts to actually read it. I was afraid its probably something serious.

IggDawg - I only wish my engine was coated in anti-corrosion compound! Then I'd know where the oil was going.

I'm gonna take it for a trip around a block or 2, and then check the level again. I'm also going to make sure its actually sitting level. (Fingers crossed)

[mikec]

Now I'm confused / pissed off / embarrassed...

So I went to get oil today, because I've gotta change it this week. Quickly checked it in the parking lot, but I didn't believe what I saw. So I drove it home, and parked it on the street. Left it to sit and drain back into the pan for a good 25 minutes or so, and I just checked it again.

The oil level is above the full mark.

Yes, somehow, while it was sitting in my driveway, and during the 6 km drive to get oil and come back, a quart of oil magically reappeared.

The only driving I did yesterday was when I moved the car onto the street, and then later in the day moved it back into the driveway. I was fairly sure where it was parked was level, but even if it isn't, its not sloped enough for a whole quart to disappear. I suppose its possible for a bit of expansion to occur, but I find it hard to believe that the driving I did caused to oil to expand enough to move the level from the L to beyond the F.

I'm going to try to measure how much comes out during the oil change, as I no longer trust my dipstick to any degree. Thanks for the help everyone, I'm going to be quiet now.

[totech]

Mike,

The dipsticks on all Subaru's are a little vague, so, It is possible that you misread it, or that the oil was hiding in the engine somewhere just to bug you.

Years ago, my father misread the dipstick on my new mustang, and added 6 litres of oil to it. so - with 10 litres of oil in it he drove over 500 kms.. he said it did not run very well...

I ended up trading it in really early, as I slowly started having to replace seals.

See you later, hope the rain stops!!

[Austin]

HOWEVER it DOES secreat a special "anti-corrosion compound" which coats the underside of the engine to prevent oxidation of the engine components .

That's what mine does...

I've got a nice leak from the oil cooler (above the oil filter)... probably need to replace the gaskets...

[Legacy777]

Mike,

Subie engines are sorta tricky. I can drive mine around the block or something.....wait 10 min and then check the oil and the level is above full mark.

However I can drive home from work (~10 mi)....wait 10 min and check the level and it reads accurately.

It has done this sporadically throughout the time I've owned it.

The only thing I can contribute this too is that if the engine comes to rest at a certain position it can hold oil in a certain spot or something like that.

If I get a real bizzare reading, I'll usually just start the engine, let it idle for a little bit.....turn it off...let oil drain back in the pain and check again.

My owner's manual says my n/a engine takes 4.8 quarts. I can usually get about that much....between 4.6-4.8 w/ filter.

[mikec]

Josh,

I was thinking maybe something like that happened to me. I'm going to see how much I can drain out of it tomorrow, which should tell me better what's going on.

It's definitely going to be happy its getting fresh oil tho! The stuff in there right now is pretty dark (using dino oil).

[mikec]

Hrm... I only drained about 4 litres out of it. That's about 3.5 quarts. Does that sound close to what anyone else usually gets?

Me thinks I was right with my original post, because I know I didn't splash that much around when I dropped the old filter into the pan

I'll drive it around a bit today and see what happens with the level.

[Legacy777]

well.....how much did you put in though?

[mikec]

About 4.5 quarts. So it looks like I may have actually been low after all, but not to the extent that I thought I was when I started this thread.

I'm going to have to see what oil consumption is like over the next month or so, and then I guess I'll take it from there.