[OffroadX]

Use the lowest octane you can unless your engine tells you otherwise by knocking. It's made to use 87, use 87. Higher octane does NOT mean more power, it actually combusts slower and at a higher temperature than the lower octane, and unless the engine is tuned to take advantage of it, you'll get LESS power, LOWER fuel economy, and if the fuel isn't combusting completely, you're sending some fuel down the exhaust as it completes the combustion process which can harm the exhaust valves, 02 sensors, and catalytic converters, not to mention increasing your exhaust emissions.

At elevations over 4000 ft, you can buy 85 octane gas and run it safely, octane requirements decrease with altitude.

Brent