May 30, 200421 yr http://www.cars101.com/subaru/outback/outback2005.html#mechanicals Found this neat little page on the new Subaru Outback specs. I have a question concerning the 2.5 XT (turbo) - Subaru recommends 91 Octane for the turbo model, but can you run 87 Octane on turbo without severely affecting it's performance? Just considering the economics with the cost of gasoline these days....
May 31, 200421 yr No, dont run anything less than 91. You can, but it will probably cause engine knock which will ultimatly lead to piston damage and probably engine failure. And with the extra $.20 a gallon, it isnt that much more per year if you do the math, it is only about $125 more every 15,000 miles to run 91 instead of 87.
May 31, 200421 yr Most modern ECUs can detect knock and adjust the spark timing to accomodate it. You'll lose some performance, and you should avoid it as much as possible. If you have to use 89 or 87 every once in a while, it'll be OK.
May 31, 200421 yr Author Thanks for replies. Not ever having owned a turbo anything, is there any other considerations in costs/maintenance above and beyond the normal routine stuff? Since the 3.0R H6 OB are a little higher than I want to spend (plus I'm not a fan of leather interiors which is all they offer), I'm seriously considering the 2.5 XT. Opinions? Anyone get to drive a 2005 2.5 XT OB yet?
June 1, 200421 yr I know the ECU can try to stop detonation but it can only do it to a point, i really dont think it would run well at all on 87 octane. There was a STI owner that put in 89 octane on accident and saidhe had horible detonation with any boost.
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