If you’re trying to decide between premium and regular gasoline, know that paying extra cash for the upgrade to premium at the gas pump might not benefit your automobile. It all depends on your specific car and your driving style. Here’s the difference between regular and premium gas and why you might—or might not—benefit from an upgrade.
The three main gas types are regular, mid-range and premium, and these types are separated by 87, 89 and 91 octane fuels, respectively. The appropriate gasoline is determined by your automobile manufacturer. If your owner’s manual recommends using premium, experts recommend using premium to get the most from your car. It will ensure that everything functions to the best of its ability.
“If your manufacturer requires that you use 91 grade of gas, you should use this grade of gas to prevent harm to your engine and avoid the risk of invalidating your warranty if something was to happen to your engine,” says Robert Hills, senior education program manager at Universal Technical Institute, which provides automotive technology education.
If your manufacturer recommends regular or mid-range fuel and you use premium, your automobile probably won’t benefit from the extra cash you spent. Even if your manufacturer recommends premium and you use regular gas, it will not harm your engine. Hills noted that using a lower grade of gas than is suggested “will affect the performance of your car and reduce your miles per gallon by about 3 to 4%.”
Unless you are an aggressive driver, in most normal driving conditions you will likely not notice any real change, according to Hills. You will simply have spent more money for similar results.
If your car was built for regular gas, that is all you need. Anything with a higher rating is more or less superfluous. If, however, your car has more advanced parts under the hood, you will benefit from more advanced gas. Otherwise, regular gas will suit your needs just fine.
The downside to regular gas is that regular fuel burns faster and can “auto ignite” before you intentionally ignite it. Hills explained, “This can lead to what’s known as ‘detonation’ or ‘knock’ which causes shock to the piston and cylinder walls and can seriously damage an engine if left unchecked.”
Long story short: Some experts say if you drive a quality car with a high-performance engine and you use regular fuel, you might be sabotaging yourself. One of the most important factors is where you purchase your gasoline. The quality of the product and the additives affect the engine more than the octane rating.