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What Are Premium Gasoline and Diesel Fuels and Are They Worth the Higher Price?

In most gas stations, next to the regular unleaded gasoline and diesel nozzles, one can find these additional pumps with labels promoting their benefits. That begs an obvious question: what are these premium fuels, and are they worth the extra price?
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They come in a variety of fancy names that contain superlatives like Premium, Super, Extra, or Ultimate, and the main reason people think twice before using them is the higher price.

Like everything in life, the better the product, the steeper the price, but what makes these fuels so special, and is it worth using them instead of the standard versions?

Let’s start with the more widely used premium gasoline, also called super fuel or high-performance fuel. It usually has a higher-octane rating than its regular counterpart, meaning it has a higher knock resistance. In even simpler terms, it’s less susceptible to self-ignite and burn in an uncontrolled manner.

The amount of octane contained by the fuel also affects how well it will perform in higher compression engines. In theory, it will improve the fuel economy and performance of the powerplant.

In most parts of the world, including the E.U., this rating stands between 95 and 98 for standard gasoline, whereas the premium versions go between 98 and 100. In the U.S., customers can choose between standard, midgrade, and premium gasoline with ratings between 87 and 94.

Does this mean that American gas is worse? Not at all, these differences are the result of using different ratings. In Europe and most parts of the world, the Research Octane Number (RON) is used, whereas in the U.S., Canada, Brazil, and some other countries, the rating shown on the pumps is an average between RON and another rating called Motor Octane Number (MON). This average rating is dubbed Anti-Knock Index (AKI), often written on pumps as (R+M)/2, which features lower digits than elsewhere in the world for the same fuel.

Premium diesel usually has a higher cetane rating than the regular version. That means that it will ignite more quickly when injected into the combustion chamber. More importantly, premium diesel contains additives that help clean the fuel injection system and prevent soot build-up. It’s also better suited for cold temperatures since the chemicals it contains provide more protection against gelling.

So, is it worth paying extra for premium fuels? Generally, yes, especially if you care about your car and plan to keep it running smoothly for an extended period.

However, most engines, whether gasoline or diesel, are built to work with regular fuels, so using them won’t harm the engine or its fuel system.

Some high-performance gas-powered engines require higher octane fuel. This information can be found in the owner’s manual; on some vehicles, it is inscribed on the fuel cap. Here, premium fuel use is mandatory since inferior rated fuel might damage critical components such as fuel pumps, fuel lines, and injectors.

With diesel-powered engines, it’s a good idea to at least fill up with premium fuel from time to time to give the system a good clean, especially since fuel pumps and injectors are a lot more expensive than those found on gasoline engines.


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