Most people are clear on which type of gas their car needs. But not as many are clear on the differences between regular and premium gas.
What’s the difference?
One obvious difference is the price—premium fuel typically costs about 20 cents more per gallon than regular gas. Premium fuel also comes with a higher octane level—92 or 93 compared to 87 for regular gas. (You may also see a midgrade gas with an octane of 89, which is less commonly used than 87 and 93.)
Octane is how much compression a fuel can withstand before igniting. A higher octane gas won’t pre-ignite or explode as quickly, which explains why high-performance cars with higher compression engines often require higher octane gas. Engines that take higher octane fuel tend to work more efficiently and emit less emissions and exhaust.
Why the right fuel matters
Cars are designed to run best with a specific type of fuel, and your owner’s manual will let you know what that is.
Still, you may be tempted to fill your car up with a different type of fuel. This is often the case when you have to fill up with more expensive 93 octane gas.
If you use a lower than recommended level, the gas may combust too fast for your engine. That can cause the engine to make a knocking noise. In addition to this unwanted noise, a lower than recommended gas can also reduce your car’s power and fuel economy and cause engine damage.
When it comes to the opposite—using a higher octane fuel than recommended—the risk of danger is lower. The general consensus is that using premium gas when your car can run on regular gas doesn’t deliver any extra benefits when it comes to engine life, fuel economy or reduced emissions. So save your money and fill up with regular gas.