Recently a Westford Patch reader saw that all the gas prices, including correlations between different kinds of unleaded gas seemed to be closely tied to other gas stations nearby.
They wondered why that was, and after some research, here's what we found out after talking to a few local gas station managers.
Ultimately, determination of gas prices in Westford has very little to do with Westford itself. While it varies slightly from company to company, people at the corporate level give station managers a baseline price and then ask for a set of criteria to determine the price that will appear on the sign near the road.
According to the U.S. Energy Information Adminstration, over the past few years, those baseline prices are driven primarily from the cost of crude oil.
The only local variable comes from competiting nearby gas stations, which are monitored for price changes. When competitors' prices change, station managers notify their superiors, with a station potentially changing their own price to compensate in a matter of hours.
Generally, these rules apply to all forms of unleaded gasoline according to managers we talked to, but prices for higher octanes of fuel are less prone to significant price drops due to the fact that only higher-end vehicles are able to fully exploit the benefit from those types of fuels.
Octane numbers at pumps are a ratio within fuel between two compounds known as iso-octane and heptane, with the percentage of iso-octane being the number seen on the pump (ex. 87% iso-octane is also known as regular unleaded, or 87 octane fuel.)
Octane itself is not a measure of energy, but a measure of a fuel's efficiency to engage in controlled ignition reactions versus uncontrolled self-ignition reactions known as "knocking," with higher grade octane fuel having few uncontrolled self-ignitions.
Thanks to certain fuel additives and refining techniques, it is possible to obtain octane values above 100 in certain cases like specialized jet fuel, as well as other compounds such as methane.