What type of gasoline should be used for an engine with a compression ratio of 8.5 to 9.5?
2 Answers
For an engine with a compression ratio of 8.5 to 9.5, use 92-octane gasoline. Fuel filling amount: Generally, filling until the pump automatically stops is sufficient. There's no need to round up to a whole number and manually add more. After filling, remember to tighten the fuel cap until you hear a click before leaving. Checking the fuel gauge: Before driving, check the fuel gauge. Calculate whether you need to refuel during your trip based on the distance and the fuel gauge reading. It's advisable to refuel in advance rather than waiting for the fuel light to come on. The fuel pump is located inside the fuel tank and operates at high temperatures when continuously working. Being submerged in fuel helps cool it effectively. When the fuel light comes on, it indicates that the fuel level is below the pump. Consistently waiting for the light to come on before refueling can shorten the fuel pump's lifespan. Having too little fuel in the tank may even cause the fuel pump to burn out. Best time to refuel: It's better to refuel in the morning or evening, avoiding the midday when the sun is strong and temperatures are high. Since gasoline is charged by volume rather than weight, it expands when hot and contracts when cold. Refueling in the morning or evening allows you to get more mass for the same volume of gasoline, saving you money.
My car has a compression ratio around 9.0. I've been using regular unleaded gasoline, about 88 octane, for years without any issues. Simply put, compression ratio refers to how much the engine compresses the air in the cylinders—8.5 to 9.5 is considered moderate, not as high as performance cars. Lower octane fuel works perfectly here because higher octane mainly prevents knocking (premature combustion of the air-fuel mixture), which is less likely with lower compression. Using premium fuel like 98 octane is just more expensive and wasteful without benefiting the engine. I’d suggest checking your owner’s manual—manufacturers always specify the right fuel grade. No need to overspend on upgrades. For engines like this, affordable regular gasoline is the smart choice—saves money and hassle.
