Subaru: 2004 Forester 2.5X High Altitude Octane requirements

I live 25 miles Northwest of Denver Colorado and I just bought a 2004
Forester 2.5X. I have only had it a few days, but so far I really feel
good about my purchase. It's my first car that doesn't carry a US brand,
although our 91 Acclaim(157,000 miles), which I traded in, and 93
Daytona(145,000 miles), which have been quite reliable, both had
3.0L V6 Mitsubishi engines.

The Forester owners manual says that I need to use 87 Octane unleaded
gasoline. Normal regular unleaded here is 85 Octane. I have seen
statements on web sites that would appear to be fairly reliable
indicating that somewhat lower Octane rated gasoline can be used
at "High Altitude" if the engine is not equipped with a turbo and is not
high compression (>11).

I have been looking around on-line and have found that Nissan/Infinity
says that it is OK to use 85 Octane gasoline in their engines rated for
87 Octane when operated above 4000 feet, which is my situation.

Has anyone seen a similar "High Altitude" exception from Subaru
permitting the lower Octane gasoline?

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Ken Wampach - LastNameATeskimoDOTcom