Back in the good old days (in this case, as recent as 2009), you could fuel up for roughly $2.35 per gallon. Those times have passed, as the national average for gas is now reaching about $3.75 a gallon, according to the U.S. Energy Information Administration (EIA).
At these prices, who would want to pay extra for higher-octane gas? Midgrade quality costs roughly $3.90, and premium costs more than $4 a gallon. Ouch.
Here’s a simple rule of thumb: When in doubt, check the octane rating recommended for your vehicle’s engine. Your vehicle manual should contain this helpful bit of information. If you can’t find it there, check with your dealer. The reason? You may be paying extra for something that your car simply doesn’t need.
“Buying higher octane other than what is recommended will not necessarily hurt your engine, but it will not increase performance,” says Neil Gussman of the Chemical Heritage Foundation, an educational and information-sharing non-profit specializing in chemistry and chemical engineering.
A common mistake, Gussman says, is concluding that all high-performance engines need high-octane fuels because they have higher compression, and that the more expensive stuff will give it the power it needs. Not true.
“Higher octane means a more controlled combustion, not more power from the fuel,” he says. “So if your engine does not require expensive fuel, buy the fuel your engine is rated for.”
In fact, you may be able to forego premium fuel even if it is recommended in the manual, according to Philip Reed, a senior consumer advice editor and expert for Edmunds.com. That’s because advances in engine technology have come so far that vehicles with the premium recommendation will often now run on regular without getting that old, much-dreaded engine “knock.” Yes, the performance will technically decline. But the difference is so slight that you probably won’t notice unless you’re a total gear head—perhaps you’ll go half a second slower from 0 to 60 mph, Reed estimates.
It wasn’t always this way, he says. In the past, engines didn’t adjust to fuels with different octane ratings. So the engine knocked audibly as fuel combustion became uncontrolled. And that would prove damaging to the engine over time.
“But today, engines monitor knock activity and adjust to quell it, effectively tuning the engine on the go,” Reed says. “This gives drivers more flexibility in the fuel grades they can safely use. If you don’t have a heavy foot and accelerate moderately, it’s difficult to notice any loss of power.”
- Fueling up (toledoblade.com)
- Preventing knock in gasoline engines (econogizer.wordpress.com)
- Suppressed Technology: Hydrolate Fuel, Water and Gasoline Mixture (ageoflucidity.info)
- Xtreme Fuel Treatment Users Testimonials (xftsavesfuel.wordpress.com)
- Why your car’s engine might be knocking (Hint: it’s not the oil) (theglobeandmail.com)