Gas Octane Ratings

July 21st, 2016


You know those buttons you push at the gas station with the numbers on them (87, 89, 91-93)? If you’re like me, you probably pick 87 because it’s the least expensive. Hey, no shame in saving money! However, do we know if that’s the right grade for our cars? Would your car benefit from using a higher, more expensive grade?

What the octane ratings mean

Before we figure out what octane grade you should use, let’s find out the meaning behind those numbers. An octane rating measures the “knock resistance” of the fuel. Generally, these numbers will be 87 for regular, 89 for mid-grade, and any number between 91 and 93 for premium. These numbers can be higher or lower, but these are likely the ones you will see most commonly. Generally speaking, lower grade octane levels are made with cheaper ingredients. What makes premium gas expensive is the fact that it was blended with more octane that can handle higher pressures without self-combusting. Every gas company is different, but they make their premium blends with more expensive ingredients, hence the higher price.

What is “knock resistance”?

Engine knocking means that the fuel within your engine is prematurely sparking and combusting on its own, causing a knocking sound. This incident is common in high compression engines, like the ones found in the 2014 Acura TSX, for example. For these kind of engines, gas with higher octane ratings should be used in order to prevent that knock from happening. Is it cause for concern if you hear your engine knock? Not always; you should only be worried if it’s a constant, hard knock. This could harm your engine, and we all know how much you want to keep driving on those beautiful TSX wheels.

Paying the price: is it worth it?

Should you always opt for the higher grade no matter what car you drive? Well, for starters, you should always check with your owner’s manual to see what kind of fuel you should be using! You could be putting regular-grade gas in a car that actually needs premium, or vice versa!

Similar to how we talked about synthetic oil last time, not every car will benefit from using premium gas. In fact, if you put premium gas in a car that doesn’t require it, then you probably just wasted your money. Your car will not perform any better with the premium gas than it would have with regular-grade gas.

So, to sum it up, a higher grade gas means less knocking in your engine. Read your owner’s manual to find out if you need to use higher-grade gas or not. If you’re still feeling questionable about it, listen to your engine. If you don’t hear a knock, then you can stick with regular gas grade. If you hear persistent knocking, try a premium gas and see how that works.


Hope this helped!
– Kathy


Please Comment