Head scratching oil burn in '16 Outback 3.6

[benjy]

interesting read! dont own or want a CVT!! manual trannys ALL + NO DI= fewer issues

 

[ChiTDI]

Are the headwinds consistent going to TX and tailwinds returning? That will do it!

 

[meep]

My older 2.2L Subaru was this same way. Oil consumption varied by a lot of factors which i never figured out. It was generally predictable on my daily commute of 450miles/week, but highway trips were totally random. It didnt generally consume much anyway, so an interstate drive of 1/2-1 qt was surprising, and then other times it didn’t use any. Mobil 1 5-30 was more random than 10-30.

 

[Rand]

it might just be fuel in the oil burning off etc.

maybe you could drive it around there for a few months then see how much you burn on the way home.

not very practical way to test but would be interesting.

 

[SilverFusion2010]

So here's an interesting one I can't seem to figure out and isn't making much sense to me...

I have a 2016 Outback 3.6 and love the car for what it is. Other than this "issue" the motor and the rest of the car are in great shape with plenty of abuse and 83k miles with most of any needed work or maintenance done by myself and have had since new. Oil changes have always been consistent at 6k miles give or take on synthetic when back in North Texas, then when moving here to Colorado at 5k for Syn and 4k to 5k for "conventional" blend depending on driving. So never any really long OCI's or even pushing it with this car in its life.

Anyway, the motor doesn't really burn much oil at all during an entire OCI...MAYBE 1/4 a quart if there's lots of off roading or mountain driving during but even then it's only sometimes and is really a non issue.

Here's the head scratcher I can't figure out....I still drive back and forth to Dallas from Denver every 3 to 4 months consistently. On the drive DOWN to Texas, I'll ALWAYS burn between 1/2 a quart to 3/4 of a quart of oil. I'll top off when I arrive of course the next day, however on the drive back to Denver the motor won't burn a single drop. What point I am in the OCI doesn't matter it seems to always happen to the same degree, and the brand or type doesn't seem to matter with the exception that I used a little bit less than usual on the drive down with a HM blend.

It's definitely not a situation where the oil has been short tripped (my car rarely is) for a while then burns off excess fuel, water etc. The motor barely burns any oil during an OCI or even long highway drives unless it's the drive down to Dallas and only then one way.

I can't figure it out and even fellow mechanic buddies can't seem to figure it out. Could it have something to do with changing altitudes or pressures going DOWN only? And where could it "be going"? Past the piston rings and into the cylinder? And then why? lol

The motor obviously seems just fine otherwise and as long as it's topped off afterwards has no issues. I've never even experienced a low oil light in the thing...but this one way drive is the only thing it doesn't seem to like. Anyone here have any experience with something like this before by chance?

first thing that occurs is that you're cooking out some fuel dilution on the trip down, and nothing left to cook out on the way back. Do you short-trip much when you're not driving to TX?

EDIT

nevermind, reread your OP.

Maybe the oil control rings are getting freed up from the extended highway driving and slowly gooping back up during your regular routine until they get loosened back up on the way to TX?

 

[Needleman]

During low speed off roading you're building fuel dilution in the oil due to lower oil temps. Then, on your trip down, oil temps get high enough to boil off all of the fuel accumulated during your normal, low temp driving. On your trip back up, there's little if any fuel accumulation to boil off, so it looks like you dudn't use any oil.

 

[Quantico]

Oh that's an EASY one.

And a sustained trip, You will be burning off the sump dilution of water and fuel, then having exercised the engine you will have cleaned up the rings a bit.
Cars that " don't burn a drop" actually DO, its unavoidable.
The missing lube is replaced by gas and water and other blowby products.

HTH,

- Ken

I think the car is burning off water and fuel in the oil on the first trip..

 

[Quantico]

Next trip. Chg oil before you leave. Might be interesting to see if it still burns oil the first direction.

 

[tojo1968]

So here's an interesting one I can't seem to figure out and isn't making much sense to me...

I have a 2016 Outback 3.6 and love the car for what it is. Other than this "issue" the motor and the rest of the car are in great shape with plenty of abuse and 83k miles with most of any needed work or maintenance done by myself and have had since new. Oil changes have always been consistent at 6k miles give or take on synthetic when back in North Texas, then when moving here to Colorado at 5k for Syn and 4k to 5k for "conventional" blend depending on driving. So never any really long OCI's or even pushing it with this car in its life.

Anyway, the motor doesn't really burn much oil at all during an entire OCI...MAYBE 1/4 a quart if there's lots of off roading or mountain driving during but even then it's only sometimes and is really a non issue.

Here's the head scratcher I can't figure out....I still drive back and forth to Dallas from Denver every 3 to 4 months consistently. On the drive DOWN to Texas, I'll ALWAYS burn between 1/2 a quart to 3/4 of a quart of oil. I'll top off when I arrive of course the next day, however on the drive back to Denver the motor won't burn a single drop. What point I am in the OCI doesn't matter it seems to always happen to the same degree, and the brand or type doesn't seem to matter with the exception that I used a little bit less than usual on the drive down with a HM blend.

It's definitely not a situation where the oil has been short tripped (my car rarely is) for a while then burns off excess fuel, water etc. The motor barely burns any oil during an OCI or even long highway drives unless it's the drive down to Dallas and only then one way.

I can't figure it out and even fellow mechanic buddies can't seem to figure it out. Could it have something to do with changing altitudes or pressures going DOWN only? And where could it "be going"? Past the piston rings and into the cylinder? And then why? lol

The motor obviously seems just fine otherwise and as long as it's topped off afterwards has no issues. I've never even experienced a low oil light in the thing...but this one way drive is the only thing it doesn't seem to like. Anyone here have any experience with something like this before by chance?

Ill be honest with you, I have never seen a Boxer engine that didn't use oil.

 

[PimTac]

I think he figured it out already. This is 2022.

 

[Bailes1992]

This almost certainly sounds like a PCV issue to me.

 

[Gene K]

I don't know which of the explanations is correct but my inclination is if it doesn't burn on the way back the long trip down may have been good for it. Definitely if the explanation is contaminants burning off.

Have you noticed the burn off being worse in the winter? That might point more to contamination burning off since the build up is worse that time of year.

Is it worse in the summer? That might point more toward actual consumption.


Awe crap, another year old thread. Sorry guys.

 

[kschachn]

The poor old OP hasn’t been on since last July. Maybe he’ll be back, one can only hope.

 

[walterjay]

Before the next trip change the oil and go down with a fresh sump of oil. This would rule out gas or oil burning off from regular driving. You may find that no oil is consumed.

 

[ARCOgraphite]

Ill be honest with you, I have never seen a Boxer engine that didn't use oil.

How many have you owned? I think we are up to #7 or 8 - I lost count
In my experience over the past 30 years, I could agree with you on that; but our last 2017 Crosstrek 2.0L and the current 2021 Outback 2.5L use nothing.
The older EJ likely needed heavier oil than the junk conventional 5W30 used back then .
Then there was a period of imporperly machine valve guides and then piston and ring issues - all with TSB and campaigns

 

[ARCOgraphite]

Next trip. Chg oil before you leave. Might be interesting to see if it still burns oil the first direction.

Yes the trip could also be freeing up gummy rings along the way.
I wouldnt think any of the sump contamination would be more than a cup or two.

Likely a combination of things.

 

[tojo1968]

How many have you owned? I think we are up to #7 or 8 - I lost count
In my experience over the past 30 years, I could agree with you on that; but our last 2017 Crosstrek 2.0L and the current 2021 Outback 2.5L use nothing.
The older EJ likely needed heavier oil than the junk conventional 5W30 used back then .
Then there was a period of imporperly machine valve guides and then piston and ring issues - all with TSB and campaigns

One, 2006 Forester, used a quart every 3k miles. Belonged to many Subaru forums and it was a common topic.