A long-standing debate over octane levels in Colorado and other Rocky Mountain states will be examined again before year’s end.
While fueling up, local motorists may notice at the pump a number “86” stamped over the regular grade option that sets Colorado and other high-elevation states apart from the rest of the country.
That “86” signifies the fuel’s octane rating, or antiknock index, which measures the ability of a motor engine to resist a knocking sound. Engine knocking is heard when the air-fuel mixture inside a cylinder is incorrect, causing the fuel to burn unevenly.
In general, automotive octane requirements in Colorado and other high-altitude states are lower by a point or two than in lower-elevation states. While Colorado fills up on unleaded rated at 85 or 86, most other states have a minimum set at 87 – mid-grade for high-altitude drivers.
Standards development organization ASTM International has a fuel quality standard, D4814. Whether that 85 or 86 regular octane needs a boost – and what the implications would be for the petroleum industry and consumers – will be discussed again in December by an ASTM gas and oxygenated-fuels subcommittee of various stakeholders. Subcommittee members vote on the issue.
Fifteen years ago, the Colorado Legislative Council contested research from the American Petroleum Institute that made the case that vehicles driven in the mountains’ lower air pressure could function as well on 85 octane as vehicles at lower elevations driving on 87.
The Colorado Legislative Council argued that theory may be valid only for vehicles predating 1984. Proponents of upping the minimum rating say engines in newer models minimize the altitude effect.
Earlier this year, a proposal before ASTM to require a minimum 87 octane across the nation failed. The proposal was bucked by high-altitude states and refineries. It failed because the majority of committee decided studies could not conclusively prove a higher octane level is needed for those states.
Mahesh Albuquerque, director of the Colorado Division of Oil and Public Safety, said his department is paying close attention to the conversation but is not advocating for change unless hard evidence shows it’s needed.
“It will cause a supply shortage in the Rocky Mountain area,” Albuquerque said. “If we went to 87 tomorrow, upgrades to Rocky Mountain refineries’ processes to produce a different product would likely have to pull in 87 from elsewhere. We just want to make sure we make data-driven decisions.”
Lower-level octane is less expensive for refineries to produce, and most operators in the industry are against, or don’t see the merits of, an increase.
Mark Larson, executive director of wholesale distributors Colorado Wyoming Petroleum Marketers Association, said General Motors supports changing the standard and “driving up costs 15-20 cents” rather than upgrading their engines.
GM Powertrain Fuels Group Manager and ASTM Octane Workgroup Chair Bill Studzinski could not be immediately reached for comment.
“Why change something if you don’t have compelling evidence that it doesn’t have a statistical difference?” said Colorado Petroleum Association President Stan Dempsey. “We think the cost of consuming would be pretty dramatic, and on the Western Slope, we can get very tight with supply.”
jpace@durangoherald.com
