<<The 87 or higher is for typical elevations. In higher elevations where 85 is sold, it works fine.>>
Pat, that had always been my understanding until a few years ago when I bought a vehicle with a Ford Triton V-10 engine. In the engine owners manual it states that the recommended octane is 87, and then states that Ford does not believe in using a fuel with less than 87 octane at higher elevations. It's very specific about this.
Of course our V-stroms do not have Ford engines and my DL 650 owners manual isn't specific about this one way or another, simply stating "Your motorcycle required regular unleaded gasoline with a minimum pump octane rating of 87 ((R+M/2) method)." It does say regular but doesn't mention other than 87 octane, at least that I could find, so I find this quite confusing.
This is of particular importance to me because my home is at 5700 ft elevation and the town where I buy most of my gas is at 5280 ft (calls itself "the mile high town") and regular is 85 octane, mid-grade 87. Wanting to err on the side of caution, I've been explicitly following the Suzuki manual and using 87 but wondering if I'm wasting my money, which, being retired, I would rather not do.
Have you, or anyone else, perhaps discussed this issue with Suzuki for clarification?
Thanks for any further clarifying input. I need it!