Which Grade of Gas Should I Use?

November 28th, 2014 by

Which Grade of Gas Do You Use? Premium Gas isn’t Always the Best Option

Going to the gas station we have all seen the three different gasoline options and the difference in price that comes with them. The most common, unleaded, is typically the least expensive option. Plus is slightly more expensive and premium is the most costly. Even though gas prices are around $2.50 a gallon for unleaded nationwide on average, prices were as high as $4.09 a gallon for unleaded in California in July 2014. With the fluctuation in gas prices, is it OK for vehicles that require premium gas to use unleaded? How do you know which grade of gas to use?

grade of gas

The gas cap on a 2015 Kia Sorento.

To determine if your car needs premium gasoline consult your owner’s manual. It should have information on the octane rating of your vehicle. The octane ratings “measure a gasoline’s ability to resist engine knock—a rattling or pinging sound that results from premature ignition of the compressed fuel-air mixture in one or more cylinders,” according to the Federal Trade Commission website. The website also states the three octane grades. These numbers are the ones that appear at the gas pump on yellow stickers.

  • Regular, usually 87 octane
  • Mid-Grade, usually 89 octane
  • Premium, usually 92 or 93 octane

Edmunds.com put together a list of cars that are recommended to use premium and a list of cars that premium is required. Many of the required cars are high-performance vehicles like Audi, Jaguar, Porsche, Acura, and BMW. The Honda Civic Si made the list as well. Of the cars that are recommended to use premium gasoline, Cadillac, Fiat, Nissan, Volkswagen and Volvo made the list.

Should I Use Premium if My Car Only Requires Unleaded?

There’s the thought that cars that do not require premium gasoline will benefit from the occasional fill-up of that type, however that isn’t the case. Others contend that vehicles that require premium, but fill-up on unleaded will ruin their car’s engine. “Engines designed for regular fuel don’t improve on premium and sometimes run worse,” according to an article in USA Today. “And today’s engines designed for premium run fine on regular, too, their makers say, though power declines slightly.”
The only time you should use a higher octane gasoline than is recommended is if your engine pings or knocks. “A few car engines may knock or ping even if you use the recommended octane. If this happens, try switching to the next highest octane grade,” the FTC advises. “In many cases, switching to the mid-grade or premium-grade gasoline will eliminate the knock. If the knocking or pinging continues after one or two fill-ups, you may need a tune-up or some other repair. After that work is done, go back to the lowest octane grade at which your engine runs without knocking.” The ping and knock sounds are likened to the sound of metal balls being shaken in a tin can.
Fisher Auto’s Kia service manager, Mike Rhodas, advises that its best to use the grade of gas that is recommended by the manufacturer. On most Kias the recommendation is 87 to 89 octane. He also said that modern vehicles have sensors that detect engine knock and will adjust the fuel trim accordingly to eliminate the noise.
Contact Fisher Auto in Boulder, Colo., at 303-245-6414 to see which grade of gas you should use. If you need minor service, check out our no appointment necessary express service, available Monday through Friday 7:30 a.m. to 4:30 p.m. and Saturday 8:00 a.m. to 1:30 p.m.