Buick LaCrosse 2.4: Should I Use 95 or 92 Octane Gasoline?

[StLane]

Buick LaCrosse 2.4 can use both 92 octane and 95 octane gasoline. Differences between 92 and 95 octane gasoline: 92 octane and 95 octane gasoline have different octane ratings and anti-knock properties. Their ignition temperatures differ. When the engine piston compresses air to perform work, 92 octane fuel ignites at 100°C while 95 octane fuel ignites at 110°C. Engine knocking: When cylinder compression raises air temperature to 105°C, 92 octane gasoline may auto-ignite, causing engine knocking. Using 95 octane fuel prevents premature ignition and thus avoids knocking. The appropriate gasoline grade depends on the compression pressure of air inside the cylinder - higher pressure leads to higher temperatures.