Kamen Posted May 24, 2016 Share Posted May 24, 2016 After a recent replacement of the transmission valve body (5EAT) at the dealership, I started getting this faint torque ripple when the engine is at low RPM and high gear (typically, around 1500-2000 RPM in 5th), and it's been suggested to me that it might be the differential. First thing I consider doing is checking it and, while I'm there, replacing the gear oil (it's 80K on the car, so - why not?) I can then look at the old oil for any burn or metal shavings. Since it's an OBXT Ltd, the differential is of the limited-slip type, so I should carefully consider the fluid. Is the Subaru EOM fluid the best to use, or have people identified a better one? Hey, it's not unheard of; for example, I'd never use OEM brake pads when I can get better quality ones for less money. Any other considerations in this case? Kamen Link to comment Share on other sites More sharing options...
Waxball88 Posted May 24, 2016 Share Posted May 24, 2016 I've had good luck with mobil1 Link to comment Share on other sites More sharing options...
762x39 Posted May 24, 2016 Share Posted May 24, 2016 For gear oil, any high quality brand name synthetic will suffice. Link to comment Share on other sites More sharing options...
Kamen Posted May 24, 2016 Author Share Posted May 24, 2016 Thank you! Kamen Link to comment Share on other sites More sharing options...
Perscitus Posted May 27, 2016 Share Posted May 27, 2016 I highly recommend Amsoil's Severe Gear 75W90 Lube. It meets and exceeds Subaru's spec for both front/center and rear diffs. Works great on older and current-gen Subarus and flushes clean after even 30-60K of use. http://www.amsoil.com/shop/by-product/gear-lube/severe-gear-75w-90/?code=SVGQT-EA For your 08 XT/5EAT look here: http://www.amsoil.com/mygarage/vehiclelookuppage.aspx?url2=2008+SUBARU+OUTBACK+E Automatic Transmission, Total Fill 5 speed TG5D7..........6.8 quarts Differential, With 5-SPD AT Front..........3 pints Differential, Rear..........1.7 pints Link to comment Share on other sites More sharing options...
Kamen Posted May 27, 2016 Author Share Posted May 27, 2016 Thank you! Kamen Link to comment Share on other sites More sharing options...
Kamen Posted May 31, 2016 Author Share Posted May 31, 2016 Couldn't find Amsoil locally and ended up using Valvoline Synthetic. The old fluid was cloudy and had a small lump at the magnet in the lower plug, no shavings or anything larger than powder; nothing excessive. It seems like it had never been changed. The service manual does only call for "inspect", but - come on, dealer/service centers to which the previous owners took it! I don't believe there is any damage, but given the torque ripple I started getting (after some transmission work, including a firmware upgrade; separate thread), to rule out any role of the rear differential in it, do you think I should send a sample to be analyzed to Blackstone Labs or the like? I will also need to change the gear oil of the front differential, now that I've seen what it looks like at the rear. The manual calls for 1.1 - 1.3 qt, so I'll need two bottles. Kamen Link to comment Share on other sites More sharing options...
fedaykin Posted June 1, 2016 Share Posted June 1, 2016 The service manual does only call for "inspect", but - come on, dealer/service centers to which the previous owners took it! Why would you expect any of them to do more work than what's required? Link to comment Share on other sites More sharing options...
Max Capacity Posted June 5, 2016 Share Posted June 5, 2016 Us with 5mt's change the tranny and rear diff fluids at 30,000 miles. Just read today where someone is using Mobil Delvac 75w90 in his... http://legacygt.com/forums/showthread.php/07-spec-b-front-diff-and-tranny-fluid-change-need-253222.html 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
Kamen Posted June 5, 2016 Author Share Posted June 5, 2016 I have been using Swepco 201 in my 5MT (WRX) for around 80-90K miles now. All I need to say is, its synchros were already worn out when I bought it (@70K, which is why I tried the Swepco), and it has kept it not just alive but shiftable (let's say that's a word) so far (~170K). Just to clear up any misunderstandings: the 5MT is the original, never had anything rebuilt, and has gone thorough multiple seasons of autocross and rallycross, and hard driving (3 clutches). Changed it every 30K or less (clutch jobs), though. Kamen Link to comment Share on other sites More sharing options...
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