Final answer:
The statement is true. At high altitudes, the air is less dense resulting in less oxygen for combustion in an engine, thus reducing the need for high octane gas. Therefore, octane grades at high altitudes are lowered compared to those at sea level.
Step-by-step explanation:
This statement is true. At high altitudes, the air is thinner (less dense), leading to less oxygen available for combustion in an engine. As a result, the need for higher octane gas is reduced. Octane rating is essentially a measure of how much compression a fuel can withstand before igniting. At sea level, with more air and therefore more oxygen present for combustion, higher octane gas is necessary to prevent 'engine knocking'. But at high altitudes, the lower air pressure reduces the need for high octane, thus, the grades of octane for gas are reduced compared to those available from gas retailers located at sea level.
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