Our Honda Accord 4 cyl is suppose to use regular unleaded 87 octane. I assume that is for operation at sea level since regular unleaded in the Rocky Mountains is only 85 octane due to the 4000-5000 ft. altitude.

 

My friend move out to Colorado and bought a new Jeep, he asked the dealer what gas to run, and the dealer told him to try and run 85 octane and see if the valves tap. If the valves did tap he was told to switch to the next higher grade of gas. I'm not sure of your year of Honda but most new ones, I believe, have the ability to adjust timing based on the octane of the fuel. To adjust for tapping and detonation. (I know my truck does, I'm sure Honda is that advanced)

I'd say try the 85 and see if you engine taps, if it does then switch to the next higher grade of gas.

 

just out of curiousity what part of the rockies are you in? I run the cheap stuff in my car 87 or 85 depending on what's available and I don't have any problems in the mountains...

 

I am a Texan, but I will be traveling to Seattle, Washington so I will be in the mountains for several thousand miles each way. I have seen a lot of pumps with 85 octane for regular unleaded gasoline when we travel in our diesel pickup/camper to Reno for the air races.

 

85 is because the reaction needs to be more violent theres less O2 at those Alts if it pings go to 87-89 if not ur gtg... but 85 should be fine