Niagara Gazette — •••
IRENE FROM BROOKLYN: My car calls for regular gasoline, but I want to use premium grade. Will this harm the engine? I’ve heard you can’t do it the other way around. However, I always thought using premium gasoline would help my car run better, even though the manual says to use regular. Is this true?
TOM: Fuel octane has nothing to do with the quality of gasoline or how the car will perform. It has everything to do with how the gas acts inside the engine. If your carmaker suggests you use regular octane fuel (87) then use it. Using a higher octane will NOT make your car run better.
Let’s look into octane ratings deeper:
What is octane? Fuel octane is a measurement of a fuel’s volatility factor in the combustion chamber. In simpler terms, octane is a measurement of how the fuel combusts in the hot combustion chamber environment.
Can I use regular gas (low octane) in my high-performance car? Different octane gas was developed to accommodate different grades of performance engines. The higher the performance engine, the hotter the combustion chamber environment, and the higher the octane used. If low octane (regular) gas is introduced into a hot, high compression combustion chamber found in high performance vehicles, it pre-ignites, creating a condition called “engine knock.” Why? When low octane fuel enters the combustion chamber, it ignites prematurely. The result is the knocking you hear. Over time, continued engine knock results in damage to the tops of pistons, cylinder head faces, and valves.
Can I use regular gas in my high performance car in a pinch? Sometimes you go to fuel up and the gas station is simply out of high-octane fuel. So what do you do? Go ahead and use regular to get to where you’re going, but don’t make a practice of it. Remember, “continued use” of low octane fuel in a high performance engine will damage it over time. Built into the performance system of today’s engine is a device called a “Knock Sensor.” This sensor constantly measures combustion chamber pressure. When it senses excessive pressure from pre-ignition, it backs off on ignition timing through the ECM. This feedback system minimizes the effects of using low octane fuel. Note I said minimizes, not eliminates. Continued use of low octane fuel in a high performance engine will damage it over time.