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2015 Subaru Outback - oil consumption test

Loved your show for decades and still do! My car currently has 78,000. It has the four cylinder engine.The oil is changed every 6,000 miles. Shortly after reaching 60,000 miles the engine warning light would come on intermittently and I would be down a half quart of oil around 4,000 miles into an oil change. After the service guy at the Subaru dealership told me the this is “normal” and within the “tolerances” that Subaru recommends of normal usage. After I told him that he is had a difficult time keeping a straight face when he said that he told me they would have to do an Oil Consumption test which involves replacing the PCV valve at the next oil change and then come in to have the consumption tested at 1,000-1,500 miles. I did all that, they said all ok, but at around the 4,000 mile mark, sure enough, it’s down at least a half quart or more. Now it would make or sense to run the same test and have me come in, not at 1,000, but at 4,000 when there actually would be detectable loss. I asked about next steps and they said they would have to do the same Oil Consumption Test and replace the PCV again. I think I am getting a runaround and Subaru is relying on a flimsy excuse to not take responsibility for the problems they have with these engines. What you think? Thanks!

One half quart after 4000 miles is very, very acceptable, in fact quite good.


To fail the oil consumption test the engine must consume one quart in 1500 miles. If your engine’s oil consumption rate is 1/2 quart in 4,000 miles you are wasting your time having it tested again.


What I think is that you should learn how to check your own oil and learn how to add a half a quart when it needs some.

ALL cars use a little oil. ALL of them! Some more than others. Yours barely uses any at all. If it gets to the point where is uses a full quart in 4000 miles, still VERY good, you don’t want to be running around a quart low.

Lots of people have come here stating that their engines failed because they never checked their oil and the engines ran dry. David, please don’t be one of those people.


You want to check first for a cam carrier oil leak as they are common on a 2015. Aside from that, oil usage is common on most engines, some more than others. In a perfect world oil would be on the full line at 10K miles which it is on my latest gen Tacoma V6. In the real world every car has its plus and minuses and boxer engines use oil. On our '16 Outback the low oil light starts flickering at 5K. It’s not even a quart low then but Subaru is playing it safe because of all the serious oil burners they made that people ran dry.

The service guy could keep a straight face because Subaru made a ton of earlier engines that got less than 1,000 miles to the quart. They said that was normal until the judge said in a class action suit that it isn’t. Subaru had been sold defective piston rings by a supplier and now had to replace them at their expense.

Bottom line, latest gen Outbacks are great cars to drive, have great styling, are comfortable, the boxer engine improves handling, and the oil usage is annoying. Next time you can get a Toyota, Honda, or Nissan and have other problems.

My best friend has an '08 Toyota Rav-4, and his engine is now consuming 1 qt of oil every 400 miles, despite having faithfully changed the oil every 5k miles/6 months. During the period when he might have been eligible for free repairs (ring replacement, IIRC), it just barely passed the oil consumption test, but w/in a year its oil consumption was becoming extreme.

When he sees my Outback, which consumes–at most–1/8 of a qt in 4k miles, he is envious.

I feel sorry for your friend. If it were me trying to fail an oil consumption test and I was going to fall an ounce short, I wouldn’t hesitate to drain some oil before going back to the dealer. It’s not strictly moral, but it’s the manufacturer who screwed
up and it’s me with the huge bill when the engine starts burning more than a quart a short time later.

As Nixon said, I am not a crook!

OP has 1/2 quart in 4000 miles consumption, he will not get any better even if new engine is installed, so doing what you suggest is indeed immoral and also will not get OP any better result.

I used to have 5 Subarus in the past, and the only thing what positively reduces oil consumption is using oil with lesser Noack on their spec, this is where Mobil 1 (great oil) is not better, but worse to Valvoline synthetic, this is what I used with a noticeable burn rate reduction. If one makes oil specs research, other brands/types can be found, I went purely from the standpoint what I could buy in local store.

I have a 14 Legacy with over 100k on it. My local driving, it consumes a quart about every 3500-4000 miles, I do oil changes every 7500 miles or so, On a road trip, the car consumes a quart about every 1100 miles so I check the oil every time I fill the gas tank. I even keep a rag tied to something under the hood just to wipe the dipstick.

BTW, keep an eagle eye on that coolant level too. The only warning you get on low coolant is a blown head gasket. For some reason, my coolant level stays right at the min mark on the overflow. It never goes below, but if I add any coolant, it goes right back down to the level, has since new. I leave it alone now but check it every time I get gas or when ever I open the hood for anything.

But, if the OP is truly displeased with the consumption of 1/2 qt in 4k miles, he might want to buy a new or nearly-new Audi, whose manufacturer states that consumption of 1 qt every 600 miles is “within normal limits”.


I don’t think DavidGebauer heard what he wanted to hear.

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My 2017 Hyundai Tucson does the same thing. It has what seems a small reservoir.
I suspect sometimes the level rises so much the extra spills out.
Like heat soaking after shutoff.
However, I see no evidence of overflow.


unfortunately he will have to get used to live with it and check his oil at least monthly

Subaru is only a good litmus test on this, any car may burn oil fast enough to run low between the changes, and if oil level is not regularly checked, an inconvenience becomes a financial disaster

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I’m sorry to didn’t read my comment correctly, I said if I had an engine that fell one ounce short of the rebuild cutoff I would drain that once before going back to the dealer.

Except everything, fill cap, dipstick, filter, drain plug all have tamper proof seals when doing an oil consumption test.

Even if I had a compromised moral code (I do not…) that would allow me to cheat on something like that, the seals on all of those apertures would essentially make it impossible to cheat. As soon as the dealership noticed that the seals had been breached, the best-case scenario might be to begin the oil consumption test anew, but it is even possible that it would be a null issue if they detected tampering.

well at least I know I am not being sold a bill of goods and I should expect oil loss.

Do synthetic oils tend to burn more than the standard oil?

I’m not sure why you made this conclusion.

Given similar specs, both would “burn” pretty much at the same rate.

Oil gets consumed because of the evaporation and the actual burn.

For the burn, I’m not sure how to evaluate this properly, but it is a parameter in specs which is called “flash point”, this is temperature at which oil will self-ignite, this temperature is usually higher for synthetic products. From what I see, oil manufacturer tend not to publish it lately, but the higher - the better, so synthetics will “burn” less.

For evaporation, you can look at Noack, as it is a direct measure how fast oil evaporates in high temperature conditions.

Compare these two for example:

The second oil “model” has half the Noack of the first one!
No wonder it is recommended for GDI engines where this parameter is quite important.

I’m not sure what the Noack of “typical” conventional oil vs. synthetic oil will be, but something tells me that “typical” synthetic will be at lest a little bit better.

I’m not suggesting it will eliminate the need for you to check the oil level and add as needed, but it will reduce the speed of oil consumption, and you catalytic converter will tell you “thanks!” for that.

In my case, with 5000 miles oil change intervals, going with lower Noack oil allowed me to avoid adding any oil between changes versus adding 0.5-1 quart.

Looked a lot like a question to me. :wink: