Why is 98-octane gasoline being discontinued?

[Myrtle]

98-octane gasoline has not been discontinued. Not all vehicles can use 98-octane gasoline; it is typically reserved for high-end cars, while regular vehicles can use 95 or 92-octane gasoline. Therefore, not every gas station carries 98-octane fuel, making it less common. 98-octane gasoline refers to fuel with an octane rating equivalent to a mixture of 98% isooctane and 2% n-heptane. The advantages of 98-octane gasoline are summarized as "two highs and two lows": higher anti-knock performance and power output, along with lower harmful substances and reduced exhaust pollution. For engines with high compression ratios, high-octane gasoline is recommended. Using low-octane gasoline in such engines can lead to abnormal combustion, causing knocking, increased fuel consumption, and reduced performance. Compared to other gasoline grades, 98-octane gasoline offers stronger anti-knock properties and higher combustion efficiency, delivering superior power. However, due to its higher grade and price, it is often referred to as "premium gasoline" and is primarily used in luxury vehicles. Standards: The government imposes strict standards on automotive gasoline. These standards not only require a certain octane rating (commonly known as the gasoline grade) but also regulate the chemical composition of gasoline. If the olefin content is too high, incomplete combustion can occur, leading to the formation of gummy deposits in the intake manifold and valve guides. When selecting gasoline grades, factors such as engine operating conditions, altitude, and atmospheric pressure must also be considered. Engines frequently operating under high load, high torque, and low-speed conditions (e.g., towing vehicles) are prone to knocking and should use higher-octane gasoline (compared to vehicles under normal conditions). In high-altitude regions, due to lower atmospheric pressure and thinner air, the tendency for engine knocking decreases, allowing for the use of lower-octane gasoline. Experience shows that for every 100m increase in altitude, the required octane rating can be reduced by approximately 0.1 units. Note: Vehicles with fuel-injection systems generally have compression ratios above 8.0. Imported vehicles labeled as suitable for China's conditions can usually use leaded gasoline; otherwise, they are designed for unleaded gasoline. Generally, the higher the gasoline grade, the higher the octane rating and the better the anti-knock performance. 92-octane gasoline contains 92% isooctane and 8% n-heptane, while 95-octane gasoline contains 95% isooctane and 5% n-heptane. Recommendation: Using higher-octane gasoline in vehicles designed for lower grades will not cause damage, but the increased octane rating alters the fuel's ignition point, potentially leading to delayed combustion. This reduces the engine's power output and thermal efficiency, resulting in poorer performance. Recommendation: Using lower-octane gasoline in high-grade vehicles can cause engine knocking. Since the octane rating is significantly lower, the fuel may ignite prematurely during the compression stroke before the spark plug fires. This premature ignition creates resistance during the upward stroke, leading to unstable engine operation. Mild knocking may only increase noise without significant engine damage, but severe knocking indicates serious engine issues, affecting driving stability and causing abnormal wear on pistons and cylinders, potentially leading to cylinder scoring.