Burning oil causes and solutions

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Burning oil causes and solutions

Postby B Grade » Thu Jul 18, 2019 10:19 am

Hi guys,

Had a service recently and had full oil change etc, dip stick shows half level, suspect oil is burning quicker than usual.

At the 200k mark now, been told my turbo could be the issue.

Any advice on a cost effective solution is always good advice.
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Re: Burning oil causes and solutions

Postby Stifull » Thu Jul 18, 2019 12:11 pm

The cause may have something to do with Subarus running a little rich which help them to run cooler but I think causes the oil to burn out of the cylinders a little. Subarus will blow smoke when you get up them and the smoke is dark so I think it must contain oil. Have a look at your owners manual... It says something like... "Oil changes are every 12500klm BUT you will need to check it and top it up between service intervals.." LOL... These engine if you want them to last need fresh fully synthetic oil and filters every 5000klm . Because the oil is being changed at a more sensible interval you can use the Ryco Z436 oil filter rather than the Z495.. The Z436 is smaller and almost half the price. We have been using them on all our rexs for years and there is now one on my Lib GT as well..My wifes WRX has done 275k and was using oil so I now feed it 15w/50 which is slightly thicker.. It uses very little now between oil changes.. by the way, it is a VERY simple thing to change your own oil if you don't already.. The first thing is take of the plastic plate under the engine and put it with your plastic plate collection.. We have 5 or 6.. You don't need them. Handy for air flow if you are doing 200kph but here all it does is make it a PITB to do stuff including changing the oil , checking for leaks etc.. Warm up the engine to get the oid circulating then drain it into a oil change tray from SCA. The sort with the know to put the dirty oil filter on to drain is the best. 17mm spanner to get the drain plug out. You may need a filter removing tool ($10) as it may be tight because the oil seal swells. Never use that tool to tighten up the new filter.. Just put it on till it's firm tight to turn by hand and check for leaks after you have gone around the block The 4 cylinders all take 4.9 liters with a filter so I just chuck in the whole bottle.. I use Nulon 10w40 Syn in the 6 liter bottle in the rest of the Subarus so don't empty one of those into you engine or you may damage something... SCA has them for 1/2 price a couple of times a year and that's when I buy 4-5 bottles..We have a LOT of hungry engines to feed.. :D If you get the oil for the right price it can cost less than $50 for awesome quality oil and a filter...
Last edited by Stifull on Thu Jul 18, 2019 12:35 pm, edited 1 time in total.
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Re: Burning oil causes and solutions

Postby B Grade » Thu Jul 18, 2019 12:24 pm

Thanks for the advice, will look into it and ask my mechanic.

Turbo replacements are quite expensive aren't they?
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Re: Burning oil causes and solutions

Postby bigBADbenny » Thu Jul 18, 2019 1:05 pm

That’s great oil consumption for a 200k car!
Oil can go out the turbo bearings, especially if you have positive crank case pressure, so clean or replace the pcv valve in the rear of the inlet manifold. When removing the tmic, check the tmic for oil from the pcv and heads return to the inlet.
Inspect the underside of the inlet for rotting from oil contamination & replace it if required.

Other consumption causes include the rear main seal, valve cover gaskets and 1/2 moons, worn valve seals, gummed oil control rings etc.
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Re: Burning oil causes and solutions

Postby B Grade » Thu Jul 18, 2019 2:33 pm

Many thanks for this advice also.

Could the turbo be a cause as well?
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Re: Burning oil causes and solutions

Postby bigBADbenny » Thu Jul 18, 2019 6:27 pm

If you really want it to be. ;)
Like I said, positive crankcase pressure can push oil past the journal bearings.

You can check for evidence of oil leaking mainly in the turbine/dump housing or inlet. If doing either, check how much play is in the shaft, iirc around 1mm play is situation normal for the stock turbo.

If there’s evidence of contact between turbine or compressor blades, the turbo is rooted, but usually you’ll be able to hear the grinding.

If everything checks out then check the pcv for stickiness, blockage or stuck.
Clean or replace.

My pcv was working but pretty varnished at 220klm when I replaced it whilst the tmic was off for installing a new stock inlet and silicone throttle body hose. I could see the inlet was struggling using an inspection mirror and a strong torch: wet with blowby oil and a but bulgey down underneath.

Its just due diligence.

My stock turbo is just fine at 270k klm, btw.
Car is tuned to 15psi and will see 17 or so when wot in 2nd gear :P
I know this because I have virtual gauges using the Btssm obdii app.

But they do just “go”, my buddy’s went around 100k klm... it looked as if the nut came off the compressor shaft end and went for a joyride on the blades. No idea what caused this, other than bad luck and my08 tbSTi lol.

The going rate for a second hand vf46 is around $300-500, $800 for a vf52, the latter will require a tune.
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Re: Burning oil causes and solutions

Postby heal@kern.com.au » Mon Jul 29, 2019 5:54 pm

Just a query when discussing oil usage and type with turbos.
I have a porsche 993 and liberty 08 gt b wagon...both being boxer engines I note that the mechanic uses mineral oil , not synthetic, in the porsche because we actually want oil to burn when it should and not gum up the works to leave a residue.
I have found that when I had a 3.2 carrera the oil would mess with the spark plugs and then went away from the synthetic oils.
Why recom synthetic in the Subie when it is known to have gummed up pipes because the oil does not burn up but leaves residue....partic if not going for long rides, but rather short stops in the city. I use valvoline classic mineral oil.
???
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Re: Burning oil causes and solutions

Postby bigBADbenny » Mon Jul 29, 2019 6:25 pm

Because lib aficionados like using “the best”.
Indeed some tuners recommend oils like delvac for its detergent properties, higher zddp, weight and more affordable pricing eg in bulk.
I’m on hpr10 but should do at least one change with delvac or similar, soon.
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