At the Pump: Should I Use Regular, Mid-Grade, or Premium Gas?

Man pumping gas

Man pumping gas | Juan Barreto/AFP/Getty Images

It’s funny, because with gas being as cheap as it is, you might as well buy premium, right? After all it’s premium, so it has to be better. But it might not be that easy, and frankly, depending on what you drive, it may not matter as much as you’d think. If you don’t believe us, ask the Federal Trade Commission.

Because here’s what most people don’t realize: Gasoline is gasoline. Premium doesn’t make your car faster, more responsive, or burn any differently than Regular. What makes Premium premium is what gets added to it, not what’s taken away. Some companies like Shell make a big deal about the detergents it puts into its fuel, and that does make some difference; it helps reduce carbon buildup in your engine, makes cold starts a little easier, and helps keep your fuel system from rusting. As a result, manufacturers from Toyota to BMW recommend it for their cars.

Gas station

Gas station | Justin Sullivan/Getty Images

It’s ‘recommend’ that’s the magic word here. We’ve come a long way from the bad old days of vapor lock, “no-knock” additives, and carburetor adjustments. Today’s electronic fuel injection systems and sensors can adjust to different types of fuel and keep your car seamlessly running no matter what fuel you’re using. But if “recommended” becomes “required,” you’d better not try anything funny. For once, the simpler, cheaper cars have the advantage; you can run Regular or Premium in your Altima. You probably wouldn’t want to do that in a Porsche 911.

Many performance and luxury cars need premium fuel because they have higher compression engines. This means that the engine was designed to handle higher octane fuels that burn hotter and leaner than Regular. If the engine doesn’t use the fuel it was designed for, it can start to knock. And if it starts to knock, you’d better shut the car off before it self-destructs. Knocking occurs when the fuel detonates before it reaches the spark plug. Remember, an engine is built to handle controlled explosions. If things are exploding where they shouldn’t be… well, you get the idea.

Gas station from the past

Gas station | George Marks/Retrofile/Getty Images

Mid-grade fuel is the man in the middle seemingly because fuel companies want to provide a middle ground. With slightly more additives, and a slightly leaner burn than Regular, it offers some benefits (you may see slightly better fuel economy), but overall, few if any manufacturers recommend it, and it won’t make your Corolla won’t run any different.

That brings us to regular, the cheap fuel, and the stuff most drivers use without so much as a second thought. Like you car, Regular unleaded has come a long way since the dark days. You don’t need to worry about fuel additives like STP to make sure your car keeps running. Regular does it just fine, and keeps most of us happy enough to pay that extra dime or so per gallon for the fancy stuff. The only issue you may face is if you drive an older (say, pre-1985) car, the now-common E10 (10% ethanol fuel) can loosen up any dirt in your fuel system, potentially clogging fuel filters, and wearing out older rubber, plastic, or even leather (common in older carburetors) parts.

Gas prices at gas station

Gas prices | Justin Sullivan/Getty Images

So to sum it all up. If you’ve got a ’63 Corvette, a Ferrari FF, or a Mercedes S-Class, use Premium – though if that’s the case, we’re sure you already knew that. For everyone else, if it doesn’t say “required” on the instrument cluster, you’re probably okay saving a few dollars and buying Regular.

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