Subaru Oil Consumption (2007 Impreza - 105K Miles)

[Dominic]

Hi everyone,

I have a mild predicament that I discovered today. I have a commute that is very short (4.5 miles) that I now drive, which is great, however it doesn't allow my engine to fully warm up. As a result I checked my oil level today after 2800 miles of commuting to discover ZERO oil on the dipstick. Normally I burn through almost a full quart of oil in 5000 miles, but this is much more severe. To find out how much oil was in my sump I performed an oil change and only drained out 2.2 quarts including all I could get out of the filter. This car also doesn't have a low-oil light, so I have to watch things carefully. Also you should know the sump is rated to 4.5 quarts and I run a larger filter so I always use 5 full quarts.

For the record this car has had synthetic oil (Synpower or Penn Ultra 5W-30) all its life. The headgaskets and clutch were recently done along with cam seals, spark plug seals, and the oil pump seal. There is zero oil drainage, coolant is clean and clear, and the car runs beautifully.

So right now my plan is to shorten the OCI to around 3000 miles, top it up with a quart every 1500 miles or as needed, and keep it running. From what I read this oil consumption is pretty normal because the oil control rings on the pistons do not fully expand until the engine is completely warmed up.

My plan B is to trade the car on a Nissan Leaf and never need an oil change again

My plan C is to try a quart of MMO to see if I just have a stuck oil control ring that might loosen up. I've read a few places where this seems to "fix" oil consumption on some vehicles. However I don't think this is going to help my vehicle that has been maintained with normal oil changes and run on pure synthetic oil all its life.

All Thoughts, Opinions, and Comments are welcome.

 

[Bandito440]

How about some heavier and/or high mileage oil?

Maxlife 10w-40
Mobil 1 HM 10w-40
Rotella 15w-40

 

[Dominic]

I'd be fine going with a high mileage and may try that, but I won't go with a heavier weight (40) because my commute is so short. A heavier weight oil would only be better if I had large amounts of fuel dilution I was trying to combat, but in this case there hasn't been any in my UOAs. The oil is quite thick already considering it's not getting up to temperature. Thanks for the suggestion, I actually forgot about the high mileage oil option (duh!) so it may help things!

 

[michaelluscher]

^^ These

...Also check your PCV.....

 

[oilmaven]

My neighbor drives her 2012 Hyundai Elantra no more than 1 1/2 miles to work everyday (essentially at the bottom of the hill). As I couldn't help myself, I told her that it'd be a good idea to drive the car on the highway for 15-20 miles a couple of times a week to avoid problems considering her ultra-short work commute. She looked at me like I was from Mars. I also know that she strictly follows the "regular" maintenance interval for oil changes at her dealer (maybe one per year) and they're using whatever bulk 5W20 dino they have. Maybe it'll be a problem later on...maybe it won't. I know that if I had a short commute like that I'd make sure the car got a decent run a couple of times a week at least.

 

[05LGTLtd]

Pennz HM 10w40 with 10-20% MMO would be good cleaning cycle. The MMO will thin down the 10w-40, so don't worry about running a too thick oil. You can try 5-6oz of MMO in the gas tank per fill if you have some left from the bottle. Run for 3000 miles and keep an eye on your oil level. The MMO is more volatile and will burn off some.

Also good call on the PCV valve. I'd just change it.

 

[Dominic]

Oh yeah the PCV is new as of 95K miles, good suggestion guys! I changed that a while back

 

[05foresterXT]

With consumption that severe, I would guess that you either have a leak or stuck / worn out rings, or some other kind of lower engine damage.

Since you just had headgasket work done, I would check for leaks in that area, also the oil pump seal, or valve cover gaskets. There is something mechanically wrong. I would not be looking for a fix in a bottle.

 

[Trav]

Any leaks? These may be difficult to spot on these engines because the front cover if installed properly will hold quite a bit of oil.
Oil pump o ring behind the pump and cam seals are a real PITA with these engines.
If they didn't get the cam seals in right they leak like mad or worse yet if they scored the shaft getting the old ones out.

I had this on one a couple of moths ago, it leaked like crazy into the front cover,someone had done a timing belt and buggered the cam seals and scored the shaft.
I used a sleeve to repair the shaft.

Pull the plugs and look if one is getting oiled.

 

[MrWideTires]

Switching to a heavy duty oil reduced the consumption dramatically in my Legacy, I'm using Rotella T5 10w30

 

[Dominic]

I'm going to call the place (independent subie shop) that did the work on the car to see if they can help me. It does seem a bit odd considering the headgaskets and seals were all done in October. I do have a warranty on the work, perhaps it's like you all say.

I also don't think there is a fix in a bottle for this.

 

[artificialist]

Disconnect the intake tubing between the throttle body and intercooler, then check for oil there.
You could have a turbo with a failing oil seal, or the hose that allows oil to drain back into the pan is full of engine sludge.

 

[DrDusty86]

Sell it. It wont get any better. My roomate has an 05 STI that he checks 2-3 times a week. I believe he averages 800 miles a quart of M1 TDT, GC, RP 15w40..MAKES NO DIFFERENCE in his car.
I've seem enough of that 2.5 JSDKGJGFFHJ whatever it's called to say they have a few design flaws. HG "conditioner" ROTFLMAO.. just design the thing right the first time. for $40,000 .. New you can buy a whole lot better vehicle

 

[05LGTLtd]

OP has 2.5i, no turbo...