I looked at the same size engines.Problem being they all required hi test gas.Some are running 87 octane in them but get better performance on the hi test. Here at higher elevations the 87 octane won't cut it. Kind of shoots the saving gas money idea down.
I thought the higher the elevation the lower the octane gas that was required? At least thats what I was told the 2.5 years we lived in Colorado Springs. 85 was the "normal" regular. Running 87 at 5-7,000 feet would be like running 89 at sea level. My Super Duty requires 87. But the manual does state 91 might give better performance when towing heavy loads in hot weather if the engine starts to ping.
