By Preston Pettit

Contributing Writer

A couple of years ago, a friend and I pulled up to a gas station to get some fuel for his 2004 Chevrolet Avalanche. After he stopped the car in front of the pump and got out of the vehicle, he began pumping 93-octane fuel into his truck. I asked him what he was doing and he said, “What? It’s a big V8, it runs better on premium fuel.” I stared at him for a minute. “Doesn’t it?” he said. Of course it doesn’t, but why it doesn’t is important.

A big pushrod V8 doesn’t need premium fuel. In fact, it doesn’t even run better on premium fuel unless it’s one of the newest generations of flex fuel V8s that feature an octane sensor as part of their powertrain control module systems. For that matter, if you have a push- rod V8 like a Chevy 350, or a Ford 302, it runs the same or worse because premium fuel doesn’t burn as well in the engine.

The salesperson who sold my friend the truck told him his Avalanche would get better gas mileage and more horsepower if he ran more expensive fuel. This was nothing more than a sales pitch to disguise the vehicle’s abysmal gas mileage as passable. I can’t list in my head how many times I have been in a car dealership and heard a salesperson say that premium fuel gives better gas mileage. When I hear this, I usually interfere with the salesperson’s efforts out of moral compulsion.

Some readers may be seeing this and saying to themselves in outrage: “Wait a minute, my Honda Civic gets better gas mileage and horsepower when I run premium fuel.” They are right. That’s because that little inline 4-cylinder motor is actually very high-tech. It has design features such as double overhead cams with some form of VTEC variable valve timing, knock sensors, octane sensors and computer controlled ignition. All of that technology makes it run better on high- octane fuel.

 Other readers may be tempted to fill their sports cars with low octane fuel even though their gas caps read “high octane fuel only,” and they would be fine doing it unless they have forced induction. The only cars that absolutely must run high- octane fuels are those with forced induction or really high compression. We’re talking turbochargers and superchargers in the land of Corvette and Ferrari here. Premium fuel is used so the engines in said cars do not get damaged with fuel pre-detonation, also known as knock.

Unless your car specifically calls for premium gas avoid paying for it at the pump.