Robe30 Posted April 21, 2015 Share Posted April 21, 2015 I've been talking to my local Subaru shop about the oil consumption on my 05 OBXT (137k). It runs great, no smoke and only a minimal visible oil seepage. I go through about 3 qts of oil per oil change (btwn 3-3500 miles), Rotella 5w40 T6. He is thinking that the oil may be disappearing via the PCV system. I replaced the pcv valve/hose last summer w/ OEM and installed a Perrin inlet hose. He recommended I look into an oil/air separator to return the oil back to the block. I know nothing about o/a setups. Would this help with my oil consumption issue? Any downsides to running one? Link to comment Share on other sites More sharing options...
Justin1390 Posted April 21, 2015 Share Posted April 21, 2015 Something like that could help, but I've never seen that much oil disappear through a PCV. Either way, a oil/air separator can't hurt, and you could always just set it up for collection to see how much is leaving. On the other hand, I might go ahead and really, really make sure you aren't leaking oil while you are driving, especially from the rear main. Link to comment Share on other sites More sharing options...
Rhitter Posted April 21, 2015 Share Posted April 21, 2015 Boxkita was running the Grimmspeed AOS I don't think it worked well for him. Sgt.Gator thinks the Crawford AOS might have caused his engine to die http://legacygt.com/forums/showpost.php?p=5124029&postcount=42 One other user (whose name is slipping my mind) had an AOS but his commute wasn't long enough and the hoses were freezing which caused massive oil leaks through the turbo (details could be slightly wrong, just going off of memory). He removed it for a daily driven car. My OBXT build Link to comment Share on other sites More sharing options...
KRM Posted April 21, 2015 Share Posted April 21, 2015 3qt/3k miles? in for #ynansb has the mechanic ever completed a compression/leak down test? im curious Link to comment Share on other sites More sharing options...
Robe30 Posted April 22, 2015 Author Share Posted April 22, 2015 We did a compression test about 25k ago and the numbers were decent and all within similar readings. The oil consumption has been like this since I bought the car at 80k a little over 2 years ago. I've been putting $$$ away for a new shortblock from Rallispec as a next winter project. I'm hoping I make it that long. Sounds like I should skip the o/a setup Link to comment Share on other sites More sharing options...
MrTris Posted April 22, 2015 Share Posted April 22, 2015 We did a compression test about 25k ago and the numbers were decent and all within similar readings. The oil consumption has been like this since I bought the car at 80k a little over 2 years ago. I've been putting $$$ away for a new shortblock from Rallispec as a next winter project. I'm hoping I make it that long. Sounds like I should skip the o/a setup Yeap. #ynansb. At about a qt/K, you're burning it, it's not "disappearing" into your PCV. And 25k was a lifetime ago, in terms of your motor. Time for another comp and leakdown. And just say No! to afermarket blocks. Get the OEM block. Link to comment Share on other sites More sharing options...
JmP6889928 Posted April 22, 2015 Share Posted April 22, 2015 Boxkita was running the Grimmspeed AOS I don't think it worked well for him. Sgt.Gator thinks the Crawford AOS might have caused his engine to die http://legacygt.com/forums/showpost.php?p=5124029&postcount=42 One other user (whose name is slipping my mind) had an AOS but his commute wasn't long enough and the hoses were freezing which caused massive oil leaks through the turbo (details could be slightly wrong, just going off of memory). He removed it for a daily driven car. Dispatch 20 was the one and it caused his fresh VF52 to blow seals on both ends in a matter of less than 3 miles. Crawford told him that the condensation forms in the return hose and freezes up (it was about zero outdoors) and doesn't allow the pressure to go anywhere so it goes to the path of least resistance which is up the turbo drain tube and out the piston ring seals. Get a new PCV and make sure all of your hoses are good when you do the rebuild. You'll not be disappointed in the $25 it costs to do it all. Link to comment Share on other sites More sharing options...
Robe30 Posted April 22, 2015 Author Share Posted April 22, 2015 Yeap. #ynansb. At about a qt/K, you're burning it, it's not "disappearing" into your PCV. And 25k was a lifetime ago, in terms of your motor. Time for another comp and leakdown. And just say No! to afermarket blocks. Get the OEM block. I'm pretty sure #ynansb translates to "you're f'd" but does it translate to you need a new short block? I've done a bunch of compression tests on previous cars but never on a Subaru. Is it worth it to have a shop do it or give it a shot at home? I imagine in a leak down test you pump a specified amount of air into the cylinder and see if it bleeds off? According to Rallispec's website, they use a new OE block from Subaru. Any reason I shouldn't go this route? I know I have a lot of research to do before I jump into this project. I've built many VW bug engines and rebuilt my BMW M20 engine from a bare block up but I'm hesitant to to build a boosted Subaru engine from the ground up. Link to comment Share on other sites More sharing options...
boxkita Posted April 22, 2015 Share Posted April 22, 2015 leaking oil over 3k is not grounds for an aos. leaking oil is not grounds for an aos. leaking oil is your engine telling something is wrong. You need to figure out where its going. If you are using an aos, it is assumed you are running your car hard (lapping/racing). Otherwise, this is worse than bling as engine damage can occur. The GS aos was a lost cause on my engine. I fully credit the KillerB oil pan with saving my engine on more than 1 occasion. The Crawford aos is based on their racing program. That it failed on a racing LGT should tell you something. CobbTuning in Portland clarified this to mean under 500hp, the AOS is not recommended. YMMV IAG makes an AOS. Check with TheFranz who just installed one. I have no info on it. Build my car Boxkita Track days Link to comment Share on other sites More sharing options...
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