How Dangerous is it to Use Regular Instead of Premium Fuel? (2024)

Gas prices being what they currently are, many motorists are wondering just how useful filling up with premium fuel really is. This is normal. Other people are questioning the potentially harmful effects of low-octane gas.

So, let’s try to address the issue described in this article’s title with the three following scenarios.

First, in a regular car, premium fuel is only needed under specific conditions (intensive use for example), and has little to no impact on engine performance or efficiency. This is what various studies have revealed, including the one led by the American Automobile Association (AAA) a few years ago.

If regular fuel is recommended, don’t waste your money on premium. But it’s a good idea to use premium occasionally because it contains more additives and detergents that can help your engine.

Conversely, if premium fuel is required by the manufacturer (as shown on the fuel filler flap) in a luxury high performance car, or one equipped with a turbo, you have your answer. Using regular gas will not only affect the engine’s performance, it will also impact its long-term health and operation, because it wasn’t designed for this type of fuel.

William Clavey

Now, what happens when a vehicle can use both? Take the various Mazda models equipped with the 2.5-litre turbocharged four-cylinder, for example. This engine loses a little bit of power (23 horsepower and 10 ft-lb) when fed with regular gas, but there’s no significant danger in doing so daily.

However,remember this: when a premium fuel engine runs on regular fuel, there’s a risk of combustion of the fuel mix before the spark plug even lights up. This causes a phenomenon called knocking, which is likely to damage the engine.

Although Mazda recommends using premium fuel, they don’t require it. Why? Because their engine doesn’t have a very high compression rate and boost pressure. In other words, this is not really a high-performance turbo engine. In everyday driving, there’s no problem using regular gas, but if you often drive up and down hills or tow, premium fuel will make the engine’s task easier.

If you have any question regarding the fuel required for a particular vehicle model, consult the owner’s manual or one of the brand’s dealerships.