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97 outback drinking oil


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Hello again everyone,

 

Im still enjoying my outback and it is running great, apart from the fact that its drinking oil, around 2 litres for every 4000 miles, and im pretty sure its going out of the exhaust as its a bit smokey especially at start up and kind of smelly. The coolant is clean and no emulsion or other signs of head gasket problems.

 

What do you think could be causing the oil burning?

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What kind of oil are you using? Are you putting additives in with it at all? Have you checked under the car to see if you can spot oil stains anywhere on the bottom of the engine? If you have an air compressor you can do a positive compression test, where you send air through the spark plug hole and then like, open the oil filler cap to see if you can hear the air rushing out. You could also just do a regular compression test on each cylinder too. I think if your piston rings are worn out you might have fuel leaking into your oil, which could cause it to burn up and exit through the exhaust. Good luck, let us know what it ends up being.
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Im currently using 15 40 oil semi synthetic for the top ups, the car seems to like it.

 

As you mention doing a pressure test through the spark plug holes, im sure that I have a problem there, I always had a problem with the bottom left spark plug lead coming off the spark plug, it seemed to do it most under accelerating hard. As my wife fell out with the local mechanic, i ended up fixing it myself with a kebab stick wedged in to keep it pressed on! Its been like that for months now without the cable popping off again.

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Factory recommendation for oil viscosity in your engine is 5w-30. 15w-40 is 300% thicker than recommended, and that may lead to excessive shearing of the oil molecules, which may be part of why your oil volume goes down so far between regular changes. It also makes your engine work harder, so that extra stress could be another part of why you're losing oil volume.

 

About the spark plug lead coming off, I don't know if that's related.

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I mean there's some credence to that approach, but if you're experiencing excessive oil shearing then switching to the recommended oil may help. Imho you're making the engine work harder with thicker oil, so the "benefit" is really a trade-off. Really though if you're losing oil then you want to actually solve the problem... putting thicker oil in is just putting a bandaid on it.
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10-40 is in the recommended list for my 95 along with 10-30 (for my climate). I found that it would lose less than a pint per 3000 miles with 10-30, and none at all with 10-40. That was years ago.

 

Now that I'm abusing the motor with thicker oil than that to support the worn bearings until a rebuild I'm experiencing the too much sheer and burning some oil again only on long trips.

 

I expect 40 wt is in the recommended list for the 97 as well as the 95 so it's only 300% too thick before warmup, and then it would be right back to spec.

 

I see my oil loss now only on long drives where sheer of warm oil dominates. On 8 miles and less the oil doesn't warm enough and I don't lose any oil over a change.

 

YMMV.

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From the 1997 Legacy Outback Owner's Manual

picture.php?albumid=2721&pictureid=12368

 

For fuel economy and engine longevity, you should go with thinner oil. Yes, it will leak more if you have an oil leak, but honestly if you have an oil leak then fix it, don't just throw in thicker oil and ignore the issue. But sure, if it's an emergency and you can't afford to fix the leak right away, use thicker oil for a month or two while you save some money.

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I wouldn't run anything thicker then 10w-30 in literally anything other then a diesel. I run 5w-30 in mine and all the Subarus I've worked on without any issues or drama. I've even run 0w-20 in mine for a short period and it ran very well and improved mpg but too much lifter tap once the weather got cold so I switched back to 5w-30
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How many miles has it done ? something in the engine is shot like valve guides or piston rings or oil ring or pistons. how much oil is on the spark plugs if you pull one out ?

 

Changing your oil viscosity will make no difference, something is stuffed.

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The car has done around 130,000 miles, so not too many miles, but enough for something to have failed like that.

 

I think checking the spark plugs on a boxer engine like this will be a bit beyond my ability, I han barely get my hand anywhere near the spark plugs especially on the right hand side of the engine. When i get time i will have to get it to a mechanic to check out, but im guessing whatever it is, it will be expensive.

 

To be honest I'm thinking about just running the car until it gives up, and meanwhile saving money to get a much newer outback or forrester. If an old car is going to cost me at the mechanic every couple of months, that money could go towards monthly payments of a nearly new car that shouldn't go wrong any time soon.

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picture.php?albumid=2721&pictureid=12374

 

There's more room to get at the spark plugs from underneath.

 

Imho if you have the engine serviced by a reputable shop, or by a Subaru dealer, sure it will cost you a little bit of money, but they'll probably give you some kind of warranty on it. I have the exact same car as you, and mine has 256,000 miles. There's another guy on this forum with over 350,000 on his (not sure exactly what year his is though). If you take care of the car, you could easily double the amount of miles you have on there.

 

That said, you could also probably still get a fair amount of money if you sold it, and you could use that money on a down payment for something newer, sure. But either some kid will buy it from you, fix it up and put 100k miles on it, or it'll end up in a junkyard to get parted out by people like you might find on this forum.

 

Either way, best of luck.

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Its not as hard to pull the one plug out thats under the battery to inspect it. Do it from the top of the engine.

 

Chances are the rest of the plugs will be similar.

 

The condition of the engine is all about how well its been looked after and the quality of oil thats been used.

 

The engine could easily be stuffed at 135,000 miles with poor maintenance.

 

Pull the oil filler cap off and look underneath it and down inside the engine, I'm guessing its not spotless and there is black buildup.

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  • 4 months later...

Update.

 

I ended up changing the oil for thinner oil, and now it is drinking much less oil, really now its not drinking much oil at all, and I would say that for a car of its age it is an acceptable amount ( almost never have to top-up)

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