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Each time you fill up at the gas station, you’ll notice there are multiple fuel options, each with distinct characteristics and intended applications. The primary fuel types available typically include regular gasoline, plus (or mid-grade) gasoline, premium gasoline, and diesel fuel. 

These different grades represent fundamentally different fuel compositions designed for specific engine types and performance requirements, and knowing which one to choose is vitally important for the health of your vehicle. Putting more expensive premium gas in a car that doesn’t require it won’t improve performance, while using a lower grade of gas than what’s recommended can lead to problems. 

To best understand the various gasoline types, we first need to understand the basics of two terms: “octane ratings” and “engine knocking.” Octane ratings are measures of fuel stability based on the pressure at which a fuel will spontaneously combust in an engine; the higher the number, the more stable the fuel. 

A higher rating means the gasoline is more resistant to what is known as engine knocking. It occurs when the air-fuel mixture in an engine cylinder ignites prematurely, before the spark plug fires, potentially damaging the engine. So the higher the octane rating, the more stable the fuel, and the better it is at resisting engine knocking (diesel, being a different fuel type altogether, experiences its own distinct type of knocking).  

With the basics of octane ratings and knocking in mind, let’s take a look at the four most common fuels available at the gas station — but no matter which one sounds right for your ride, it’s always best to check your vehicle’s manual before filling up. 

Regular Gasoline: The Standard Choice

Regular gasoline, typically rated at 87 octane, is the most commonly used automotive fuel in the United States. This fuel grade is formulated to meet the basic requirements of most standard passenger vehicles, including sedans, SUVs, and trucks with naturally aspirated engines (engines in which the air intake depends on atmospheric pressure alone rather than requiring forced induction). 

From an economic perspective, regular gasoline offers the best value for vehicles designed to use it. Putting premium fuel in an engine designed for regular gasoline provides no performance benefits and is, to put it bluntly, a waste of money. The engine management systems in vehicles designed for regular fuel are calibrated to optimize performance and efficiency with 87 octane fuel, making it the logical choice for most drivers.

Plus Gasoline: The Middle Ground

Plus gasoline, also known as mid-grade or intermediate gasoline, typically carries an octane rating of 89. This fuel grade occupies the middle ground between regular and premium gasoline, both in terms of octane content and price. Plus gasoline is often created by blending regular and premium gasoline at the pump, though some refineries produce it as a distinct product.

Mid-grade fuel accounts for only about 7% of all gasoline sales, and it’s likely that at least some of those sales are the result of drivers who unnecessarily purchase plus gasoline thinking it offers some kind of benefit when regular gas would do exactly the same job. Plus gasoline represents a compromise solution rather than an optimal choice for most vehicles. 

So then, why does it exist? The only real application for plus is in vehicles that experience slight knocking with regular fuel — typically older vehicles from the 1980s and 1990s — but that don’t require the full octane rating of premium gasoline. Among cars sold today, hardly any actually require mid-range, 89 octane gas, apart from some RAM 1500 trucks, Dodge Durangos, and the Jeep Grand Cherokee. 

Premium Gasoline: High-Performance Fuel

Premium gasoline is any gas with an octane level of 91 or greater, with 91 octane and 93 octane being the most common versions of premium gasoline available at gas stations in the United States (93 octane is sometimes called “ultra” or “super-premium”). 

Premium is specifically formulated for high-performance and luxury vehicles. It contains a higher concentration of octane-boosting compounds that allow it to withstand higher compression and temperature without pre-igniting. This gives it superior knock resistance, making it ideal — and in many cases essential — for vehicles with high-compression engines, turbochargers, or superchargers. 

Putting premium gas in a vehicle designed to run on regular‐grade fuel offers no benefits: It won’t produce more horsepower, improve fuel economy, or result in lower tailpipe emissions. However, due to its superior-sounding name, many consumers confuse premium gas for “better” gas. 

In 2016, the American Automobile Association found that 16.5 million Americans ignored manufacturer recommendations for regular gasoline and instead used premium, unnecessarily spending a whopping $2.1 billion per year on premium‐grade gasoline when regular would have worked just as well. 

Today, more vehicles require premium gasoline than ever before. More than half of all light-duty models (as opposed to heavy-duty vehicles) sold in 2024 require premium, including the Chevrolet Suburban, Dodge Durango, Nissan Z, and Toyota GR. Some new-vehicle buyers may not realize they’ve purchased a model that requires the more expensive type of gas until after they’ve already taken the car home, so it’s important to always ask in advance to get the full scoop on what you’re signing up for. 

Diesel Fuel: A Different Option Altogether

Gasoline and diesel are both fuels derived from petroleum, but diesel represents a fundamentally different approach to automotive power, utilizing compression ignition rather than spark ignition. Diesel has a greater energy density than other liquid fuels and is typically used in vehicles requiring high torque and fuel efficiency, such as commercial trucks, most construction and farming vehicles, and other heavy equipment. Gasoline, on the other hand, is used for vehicles that require more horsepower and that favor speed over brute strength. 

As a vehicle owner, it’s vital to know whether your vehicle runs on gas or diesel. However, it’s actually quite difficult to accidentally fill up your car with diesel if it takes gasoline, because most diesel fuel pump nozzles have a larger diameter filler pipe than gasoline nozzles.

If you do manage to put diesel in a non-diesel vehicle, it’s best to not start the engine and instead call a mechanic right away. Your car may move a few miles, but it will then likely come to a stop, potentially causing cylinder and timing issues in your engine that could cost thousands of dollars to repair.

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It’s a hot summer day and you’re enjoying that perfect scoop of ice cream to beat the heat. But then — ow! —  a sharp zing of pain shoots through your mouth. Or maybe you’re at the movie theater, savoring some Junior Mints or Skittles when that jolt of discomfort kicks in.

If you’ve ever winced while eating ice cream, sipping an iced coffee, or biting into a candy bar, you’re not alone. Millions of people deal with tooth sensitivity, and while it may feel alarming, the reasons behind it are usually simple, rooted in our evolution as a species. Let’s explore what’s really happening when your teeth react to cold or sweet foods — and what you can do about it.

Teeth Are Tough, But Also Sensitive

Your teeth may look like simple little bones, but they’re far more complex, and more sensitive, than they seem. Each tooth is made up of multiple layers. The outermost layer, enamel, is the hardest substance in your body and serves as a protective shell. Beneath the enamel is dentin, a more porous material filled with microscopic tubules. 

Those tiny channels lead to the pulp, where your tooth’s nerves and blood vessels live. When enamel wears down or gums recede, the dentin gets exposed — and that’s when discomfort can start. 

Cold drinks and food can be especially painful because they cause rapid temperature shifts in the mouth. Those sudden drops in temperature move quickly through the dentin’s tubules, stimulating the nerves and producing that painful zing. Cold tends to cause a more abrupt shift than heat, which is why it often provokes a sharper, more intense response. 

Sweet foods introduce a different challenge; sugar can seep into those open channels and irritate the nerves directly. It also feeds the mouth’s bacteria, which produce an enamel-weakening acid as a byproduct. While cold is the most common culprit, even hot or tangy food and beverages can lead to pain if the dentin is already exposed. This all adds up to a cycle of sensitivity that’s surprisingly easy to trigger.

Our Teeth Can Become More Sensitive as We Age

Tooth sensitivity often becomes more noticeable as we get older. That’s because the protective layers around the nerves — enamel and gum tissue — gradually wear down over the years. Brushing too hard or using a stiff-bristled toothbrush can also contribute to enamel erosion and gum recession. 

And once the roots of your teeth are exposed, they’re especially vulnerable to pain. Unlike the crowns of your teeth, roots aren’t covered by enamel — just a thin layer of a specialized calcified substance called cementum that can easily wear away.

Other common causes of sensitivity include nighttime teeth grinding (bruxism), which can wear down enamel over time, as well as recent dental procedures such as fillings or deep cleanings, which may leave teeth temporarily tender. A combination of age, daily habits, and gradual wear-and-tear makes older adults more prone to feel that sudden sting when eating or drinking cold, sweet, hot, or even sour foods.

Teeth Weren’t Always Tools for Chewing

So as we age, our teeth may become more vulnerable — but that sensitivity isn’t a mere design flaw. In fact, it may be a feature that dates back hundreds of millions of years.

Recent research on ancient fish fossils reveals that teeth didn’t originally evolve for biting or chewing at all. The earliest tooth-like structures appeared more than 465 million years ago as part of the tough, armored skin of jawless fish. 

Those structures weren’t for eating — they were for sensing. Embedded in bony plates, they likely helped fish detect subtle changes in their environment, acting more like pressure or motion sensors than tools for eating food.

Over time, as fish evolved jaws and began snapping at prey, those sensory structures migrated inward and became specialized for biting and processing food, but they never shed their original function entirely. Even today, teeth are wired to be highly sensitive, especially to changes in temperature, pressure, and chemical composition. In a way, that sharp pain you feel when you sip something cold is a throwback to an ancient biological function: Your teeth aren’t just for chewing — they’re also essentially little environmental sensors in your mouth.

That Twinge May Be Your Tooth Demanding Attention

Occasional tooth sensitivity isn’t always cause for concern, but if the discomfort becomes frequent or intense, or if it lingers, it could point to something more serious such as a cavity, cracked tooth, or gum disease. Teeth are excellent messengers when something’s not quite right, and they typically won’t stop signaling until you do something to alleviate the pain.

Understanding the root causes of sensitivity can help you respond with more care and less worry. Small changes, including avoiding overly acidic foods or switching to a softer toothbrush or one specifically meant for sensitive teeth can make a big difference over time and make it easier to enjoy your favorite dessert.

So the next time you feel that sudden zing after a cold drink or sweet bite, you can thank evolution — and take it as a gentle reminder to give your teeth a little extra care. After all, they’re millions of years in the making.

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We all have some preconceived notions about how certain things sound, often shaped by movies, television, and our own assumptions rather than reality. If someone tells us a story involving a noisy scene, our brain tends to fill in the gaps and is quite capable of imagining a particular sound even if we’ve never heard it in real life. 

This can lead to some surprising disconnects between expectation and reality. Some things are much quieter than we expect, others produce entirely different tones, and some make no sound at all despite our certainty that they should. Here’s a look at a few things that don’t sound the way we think — starting with our own voices. 

Our Own Voices

For many of us, listening to a recording of ourselves speak is a truly cringeworthy experience. This phenomenon is so common that the negative reaction even has a name: voice confrontation. When recorded, our voices don’t sound like we think they should partly because a recording removes the sounds we hear internally through the bones in our head, which produce deeper and lower frequency vibrations. 

As such, our recorded voices can sound higher in pitch than we’re used to, which can be surprising and not entirely pleasing to our ears. In general, however, the more we listen to recordings of ourselves speaking, the more accustomed we become to how we sound to other people, and the less it makes our skin crawl.

Punches

If we’re lucky, we’ll live our lives without ever being on the receiving end of a proper punch. And yet, we all tend to have a certain idea of what a punch sounds like, even if we’ve never gotten (or given) one or even heard one close-up. Once again, this is largely thanks to TV and movies, whether it’s the Bam! Kapow! of the original Batman series or the epic thwacks and smacks of action films such as Rocky and John Wick. 

But real punches — as well as kicks, chops, and slaps — don’t tend to produce anywhere near as much noise as they do on the big screen. Actual physical strikes create much duller, less dramatic sounds — more like a thud than a crack. In movies, these noises are deliberately heightened, with sound effects departments using all manner of techniques to create a dramatic punch effect, whether it’s by smacking a piece of raw meat with a leather-gloved hand or socking a cabbage.

Submarines

When we see submarines in movies, they’re almost always gliding through the water while emitting a constant pinging sound and carrying a chatty crew. In reality, submarine operations are normally carried out as silently as possible, with crews speaking in whispers or not at all, avoiding all unnecessary noise — including that constant pinging, which would be counterproductive on most missions. 

While the sonar operator may hear some pings, the rest of the crew often hear nothing at all. Divers are sometimes able to hear active sonar sounds coming from subs out in the water, which they normally perceive as a mid- to high-pitched noise, but not that classic Hollywood ping. And sometimes the sonar emits an ear-piercing shriek — enough to spook even the most seasoned underwater adventurers.

Car Crashes 

We’re all familiar with what cars sound like on a day-to-day basis. But when it comes to less common vehicular events such as car crashes, our expectations have often been misled by Hollywood. Car crashes in real life can be noisy, traumatic events, but they are rarely as loud as depicted in the movies, which tend to feature an excess of shattered glass and twisted metal, followed by unrealistic explosions. It’s almost impossible for a car to explode the way they do in Hollywood films, and vehicles also rarely catch fire. 

Another common movie sound effect that makes car aficionados grit their teeth in frustration is the ubiquitous screeching tire. Foley artists — the people who add sound effects into movies in the post-production process — sometimes get carried away in chase scenes, making tires squeal excessively on gravel, dirt, wet pavement, and even snow and ice (looking at you, James Bond) — places where tires don’t normally screech.

Silencers on Guns

Silencers, also known as suppressors, significantly reduce the noise made when firing a weapon. In the movies, however, that noise is often reduced to unrealistic levels, with the gun hardly making any noise at all.

In reality, even the most effective suppressors on the smallest caliber firearms can only reduce the peak sound level of a gunshot to around 110-120 decibels. An unsuppressed gunshot can reach up to 160 decibels, so the noise reduction when using a suppressor is significant — but far from the whisper-quiet shots depicted in many films.