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Guest Message by DevFuse

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Sudden excessive oil consumption

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9 replies to this topic

#1 powderhound


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Posted 01 August 2014 - 03:14 PM

95 legacy 5mt 211K.  The engine was gone over with new headgaskets, new tbelt, new seals everywhere @202K.  Recently the engine has started using a lot of oil.  I can't say right now how much how fast but it goes down daily driving ~80mi/day.  There are no leaks.  I pulled the hose off the pcv and it was wet with oil.  The pcv was replaced with the engine overhaul.  My only other issue is on a warm restart the engine will search for idle much like after an ecu reset.  It drops down below 500 saves itself then eventually idles normal.  This issue began right after the overhaul and I was waiting to see if it would go away.  It hasn't.  Oh, also threw P420 recently I assume due to the honeycomb being soaked with oil.  I reset that and it hasn't come back on.  So I'm wondering what the cause of the oil use is.  Is it possible I got a bad pcv or is there somewhere else I should be looking? 

#2 Fairtax4me



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Posted 03 August 2014 - 09:58 AM

New PCV valve? Is it Subaru or aftermarket? I have seen problems with aftermarket PCV valves.

Did you reseal the oil pan? There is an o-ring on the tube in the pan that seals against the block where the separator plate chamber is. If that o-ring is gone it will suck oil through there and increase consumption.

Low idle when warm could be dirty or misadjusted idle air control. Or the throttle cable could be just a little too tight.

#3 powderhound


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Posted 01 September 2014 - 09:35 AM

It's a genuine subaru pcv.  I've driven 400 miles since the last oil change and it's down 1/4 to 1/2 quart.  Let's call it a 1/3.  The problem I'm having is the oil level is hard to read.  One side of the dipstick is 1/2 quart low and the other side appears full.  I had this issue with a previous 92 I owned.  Never had this problem until all the engine work was done.  It's frustrating as I really have no idea how much oil is in there.

#4 mikec03


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Posted 01 September 2014 - 12:05 PM

The oil dipstick enters the oil pan at only about a 35 deg angle, and the bottom mark on it is just at the edge of the pan when the dipstick is fully inserted.  The problem of reading the level is:  when you pull out the dipstick, it sweeps oil up the tube a little ways.  If you then wipe the dipstick and immediately reinsert the dipstick, it read the oil that is still draining back into the pan.


The solution is to wait a couple of minutes after removing the dipstick.  Ideally, you are doing a gas fill up when you want to check the oil level, so remove the dipstick, fill the gas tank, and then reinsert the dipstick and read it.  The top of the dipstick is more accurate because the bottom is in contact with the oil still draining down the bottom of the tube.  You should read the oil level when the engine is hot to lessen the effect of this.

#5 MilesFox


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Posted 01 September 2014 - 05:16 PM

Orient the dipstick so the symbol is upright facing you. Read the higher side of the dipstick in this manner. There are 2 full mark. The top mark is at rest, cold engine with all the oil in the sump. The lower full mark is warm engine, with volume of oil in the upper engine and filter. Assume the higher side of the dipstick to read regardless of dipstick prientation.


The ring in the oil pan gasket is a likely culprit.


consider 5w40 oil

#6 forester2002s


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Posted 01 September 2014 - 08:10 PM

I agree that it is difficult to get a good reading on a Subaru dipstick. This is a long-standing problem that Subaru should have fixed years ago.


I always check my oil at home in the morning, after the car has been standing cold all night. Even then it is difficult to get a consistent reading.


One consolation is that, when the oil level gets to about 1-litre below full, it is very obvious, because the dipstick is virtually dry.

#7 Gloyale


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Posted 02 September 2014 - 11:53 AM

If they reasealed the oil pan they may not have used a new O-ring at the back of the pan.  That o-ring seals the "drain back" tube that is supposed to be sealed, and submerged at it's bottom in liquid oil.........when this o-ring leaks it can suck oily vapors from near the bottom of the pan.


I would suggest perhaps pulling the pan and resealing it??

#8 powderhound


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Posted 09 September 2014 - 12:32 PM

Mechanic says oring(s) in the pan were replaced.  I have switched to 10-40 oil.  Waiting to reinsert the dipstick has helped with getting an accurate reading.  I was already aware of the need for the dipstick logo to be correctly orientated.  So at 500 miles now it has used 1/2 qt.  Before all the engine work and with an external leak it was using ~1qt/3000.  1qt/1k seems excessive to me.  I've read a few posts saying new heads/valves on old bottom end can cause oil consumption.  Is that basically it at this point...the rings are leaking?  Is there anything I can try to clean them or better verify that is the issue?  Am I causing damage using 1qt/1k as long as I keep it filled up?  tia

#9 mikec03


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Posted 09 September 2014 - 01:21 PM

Check to see if the mechanic used a gasket on the oil pan.  This is a no no, although it is widely done.  The gasket on the drain line in the rear of the oil pan is not an o-ring although I don't doubt some o-rings will seal it.  I personally would not take that chance [and didn't].  The gasket is supposed  to be a flat gasket and, if a pan gasket is used, the compression on this gasket will not be sufficient.  Yes, it's a goofy design, but it is what it is.


I just had a mechanic replace the oil pan on a used 95 I bought in order to reduce the oil usage.  I had stand there and argue with the mechanic not to put on the pan gasket.  Good thing I was there.  The result was that the oil consumption went down from 1 qt/900 mi to 1 qt/2500 mi.  This is tolerable.  I have little doubt that your mechanic screwed up the pan installation.  Good luck.    

#10 powderhound


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Posted 09 September 2014 - 02:28 PM

No gasket on the oil pan.  I trust my mechanic implicitly.  He only works on Subarus.  He is human though.

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