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Discussion Starter · #1 ·
TL/DR upfront: 2013 WRX, ~70,000 miles, consumes ~ 1 QT/1000 miles, no smoke from tailpipe, minimal oil in intercooler, installed IAG AOS anyway - no improvement, consumption has gradually increased over time, prefer to do my own work, stage 1 Cobb tune


Hi guys,

I think my oil consumption is getting high enough to be considered excessive. I would like to try and narrow down the source. I don't really trust the local shops around town, and I prefer to do my own work where possible. I am the original owner and used Subaru synthetic for most of its life, oil changes every 3750. When the consumption became noticeable, I also tried Rotella T6 and German Castrol with no luck. While changing my oil, I noticed a small oil amount of oil under the turbo. Not enough to account for the consumption, but maybe a sign of a worn out turbo?

I've been reading some suggestions in other threads. What would you try next?

1. Pull downpipe and check for a film of oil. Feel for excessive play in turbo.

2. Leakdown or Compression Test. I don't have a compressor, so I would probably have to take it to a shop for a leakdown test. Would a compression test be useful at all?

Additional suggestions are welcome. Thanks!
 

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Yes. A compression test can give you a good idea if you have leaking around the piston. It works best when you have an accompanying leakdown test but it’s a good place to start.

To be honest my first suspect would be the turbo. However I’ve been wrong in the past so take that for what it is.
 

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Your stated consumption is not abnormal.
 

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Discussion Starter · #5 · (Edited)
Finally got around to doing a compression test. Values are pretty low, but relatively consistent. I suspect the low numbers could be due to the cheap amazon compression tester and cold engine. I think this rules out a damaged piston...

Cylinder 1: 110, 110
Cylinder 2: 105, 105
Cylinder 3: 105, 103
Cylinder 4: 100, 98, 100

I'm considering pulling the down pipe off the turbo and looking for oil and excessive shaft play. While I have it taken apart, I might as well install a Cobb downpipe right? If the turbo looks to be the culprit, I'll replace the turbo at the same time. Otherwise I'll live with the oil consumption.

Would you guys do anything different?

Edit to add: All four plugs looked good too.
 

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I stand by my previous assumption and also agree with previous posts that as sad as it sounds a quart every thousand or so miles isn’t unheard of
 

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Discussion Starter · #7 ·
That is sad. I may have to just accept it.

I wasn't satisfied with my cold compression test results so I re-tested with a hot engine. This gave ~ 5-10 psi increase. Then, later this afternoon after the engine had cooled, I did another cold test with a co-workers compression gauge. This one read ~ 15-20 psi higher than my original gauge, but still lower than normal.

The coworker that I borrowed the second gauge from used to be a mechanic. He says that he has been able to improve Subaru compression significantly using Seafoam, 1 can in the crank and one through the intake. He says that boxer engines can have issues with sticking rings and that Seafoam will free them up. Thoughts?

All data listed below.

Cold engine, Shankley compression tester, Only 1 plug removed at a time
Cylinder 1: 110, 110
Cylinder 2: 105, 105
Cylinder 3: 105, 103
Cylinder 4: 100, 98, 100

Hot engine, Shankley compression tester, All plugs removed
Cylinder 1: 115, 115
Cylinder 2: 114, 114
Cylinder 3: 110, 110
Cylinder 4: 109, 109

Cold engine, Coworker's compression tester, All plugs removed
Cylinder 1: 130, 130
Cylinder 2: 127, 126
Cylinder 3: 124, 124
Cylinder 4: 115, 118, 117
 

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If your car has a PCV system make sure it works.

Other than that I’d keep oil in the car and drive it forever.
 
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