Originally Posted by Marco620
You don't need that high of an octane at that high of an elevation
While most modern cars will be okay, I still wouldn't use 85 in anything fuel injected, naturally aspirated or not.
Op, manual does say you can use 91, but I wouldn't go any lower than that.
Use premium unleaded gasoline meeting ASTM specification D4814 with a posted octane rating of 93 — (R+M)/2. If unavailable, unleaded gasoline with a posted octane rating of 91 may be used, but with reduced performance and fuel economy. If the octane is less than 91, the engine could be damaged and the repairs would not be covered by the vehicle warranty. If heavy knocking is heard when using gasoline rated at 93 octane, the engine needs service.