Under the Hood

What’s The Difference Between 87, 89 & 91 Fuel?

March 15, 2019

When you pull into a gas station, you probably fill up with the same type of fuel each time. But have you ever wondered which type is best for your car? Have you ever wondered what those numbers meant? Have you ever wondered what the purpose of life is?

Well, a friend of mine tweeted recently, asking what the difference was between these fuel grades. So, after speaking with the friendly technicians at a friendly Kansas City auto service center, I’m ready to give you some answers to two of those three Qs (you can guess which ones). Here are some of the key differences between 87, 89, 91, and other fuel grades.

What types of fuel grades for cars are there?

Most standard gas stations you’ll encounter offer these three common types of unleaded fuel grades, or octane levels:

  • Regular (87)
  • Mid-grade (89)
  • Premium (91)

Other, more uncommon fuel grades include Low-Grade (85) and Super Premium (93).

What is an “octane level”?

Gasoline octane levels, also referred to as octane ratings, measure the fuel’s resistance to “engine pinging,” which is the rattling sound that emits from an engine during acceleration. The higher the fuel octane rating, the less noise will be noticeable on combustion.

Additionally, octane levels also reflect the fuel’s burn-rate. Regular 87 fuel burns slower than Premium 91 fuel, which will burn hotter and create more combustion. This is why most day-to-day cars can be filled with regular unleaded, while performance vehicles warrant Premium.

(In laymen’s terms, if you coat a piece of cloth in Regular 87 and another in Premium 91, theoretically the Premium 91-soaked cloth will burn up faster.)

Is a higher octane fuel worth the price?

If you drive a Camry or Accord, you’re better off settling with Regular Unleaded 87, which is normally 20 or 30 cents cheaper than Premium. There are no advantages to filling a normal vehicle with Premium gas, aside from knowing you’re giving your car a treat.

Should you notice your vehicle “pinging” on Regular 87 Unleaded, try upgrading to the Mid-grade 89 option. Keep an eardrum open for continuing noises, as they could be indicative of another problem altogether.

A high-performance vehicle, on the other hand, may specify the need for a higher-octane fuel, such as 91 or 93. If you aren’t sure which fuel grade to choose, check your owner’s manual or ask your dealer for advice.



What about you fine folks? Do you fill up with Regular or Premium Unleaded? Can you feel a difference in performance? Leave me a comment and #letschat!




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