Gasoline is something we use almost every day, but most people don’t think much about it. When you pull up to the pump, you usually see different types of gasoline, marked by numbers like 87, 89, or 91. These numbers refer to the octane rating of the fuel. You may wonder what that means, and more importantly, which one you should be using in your vehicle.
Choosing the right gasoline isn’t just about saving money at the pump. It also affects how your engine runs, how long your car lasts, and how much pollution it creates. This article will help you understand the different types of gasoline, what the numbers mean, and how to know which one is right for your car or truck. We’ll keep the language clear and simple so that everyone can understand—even if you know nothing about engines or fuel.
Let’s take a closer look at the types of gasoline available, why octane matters, and what happens when you use the wrong fuel.
Understanding Octane Ratings
What Is Octane?
Octane is a number that shows how well gasoline can resist “knocking” in your engine. Knocking happens when the fuel-air mixture in the engine ignites too early. When this happens, it can cause a knocking or pinging sound. More importantly, knocking can damage your engine over time.
The higher the octane number, the better the fuel can resist knocking. Here are the most common octane ratings in the United States:
- 87 Octane – Regular Unleaded
- 89 Octane – Mid-Grade or Plus
- 91–93 Octane – Premium
Why Octane Matters
The octane rating is especially important in cars with high-performance engines. These engines create more heat and pressure in the cylinders. They are designed to use fuel that won’t ignite too early. Using fuel with too low an octane number can lead to knocking and long-term engine problems.
If your car was designed for 87-octane regular gas, it doesn’t need premium. In fact, using a higher-octane fuel in a car that doesn’t require it usually won’t improve performance or fuel economy.
Types of Gasoline at the Pump
Regular Gasoline (87 Octane)
This is the most common type of gasoline in the United States. It’s called “regular” and is the cheapest option at the pump.
Best For:
- Most standard cars, sedans, and small SUVs
- Cars with engines designed for regular fuel
Pros:
- Less expensive
- Works fine for most vehicles
Cons:
- Not suitable for high-performance engines
Mid-Grade Gasoline (89 Octane)
Mid-grade fuel has a slightly higher octane level. It’s not commonly required by most vehicles, but some recommend it.
Best For:
- Vehicles that recommend but don’t require mid-grade
- Drivers looking for slightly improved performance
Pros:
- A compromise between regular and premium
- May reduce engine knocking in older cars
Cons:
- Costs more than regular
- Often unnecessary
Premium Gasoline (91–93 Octane)
Premium gas has the highest octane rating and is usually recommended for high-performance or luxury cars.
Best For:
- Sports cars
- Luxury vehicles
- Turbocharged engines
Pros:
- Prevents knocking in high-compression engines
- Supports peak engine performance
Cons:
- More expensive
- Offers no benefits in engines that don’t require it
How to Know What Gasoline Your Car Needs
Check the Owner’s Manual
The easiest and most accurate way to know what type of gasoline to use is to check your vehicle’s owner’s manual. It will clearly state the recommended and required fuel types.
- “Required” means you must use that fuel.
- “Recommended” means it’s suggested for best performance, but not essential.
Look at the Fuel Door
Some vehicles also have a label inside the fuel door. It may say something like “Premium Unleaded Fuel Only” or “Regular Unleaded Fuel Recommended.”
Understand Engine Types
- Naturally Aspirated Engines: These engines usually run fine on regular gasoline.
- Turbocharged Engines: These engines often require premium gasoline because they generate more pressure and heat.
- High Compression Engines: These engines also need higher-octane fuel to prevent knocking.
What Happens If You Use the Wrong Gasoline?
Using Lower Octane Than Required
If your vehicle requires premium gasoline and you use regular, it can cause:
- Engine knocking
- Reduced performance
- Possible long-term engine damage
- Lower fuel economy
Some modern engines have knock sensors that adjust the timing to protect the engine, but it still may lead to reduced power and efficiency.
Using Higher Octane Than Needed
If your vehicle is designed for regular gasoline, using premium won’t help. It won’t improve fuel economy, performance, or engine life.
In most cases, it’s a waste of money.
Special Gasoline Types
E85 Ethanol Fuel
This is a mix of 85% ethanol and 15% gasoline. Only vehicles labeled “flex-fuel” can use it.
Pros:
- Can be cheaper in some areas
- Burns cleaner
Cons:
- Lower fuel economy
- Not available everywhere
Non-Ethanol Gasoline
This is gasoline without ethanol. Some people use it in older cars, boats, or power tools.
Pros:
- Can be more stable in storage
- May improve mileage slightly
Cons:
- Often more expensive
- Harder to find
Fuel Tips to Keep Your Engine Healthy
- Use the Right Fuel – Always follow your manufacturer’s recommendation.
- Fill Up at Reliable Stations – Use stations that sell “Top Tier” gasoline for better engine cleanliness.
- Avoid Overfilling – Stop when the pump shuts off automatically. Overfilling can harm your fuel system.
- Don’t Mix Fuel Types – It’s okay once in an emergency, but don’t make it a habit.
- Drive Smart – Gentle driving helps fuel efficiency more than changing fuel grades.
Conclusion
Choosing the right gasoline for your vehicle is simple once you understand the basics. The most important step is to follow your car manufacturer’s recommendation. If your engine was built for regular gas, there’s no need to pay more for premium. On the other hand, if your vehicle needs high-octane fuel, don’t take shortcuts—use the right grade to protect your engine.
By using the correct fuel and filling up at reputable stations, you help your engine run smoother, last longer, and produce fewer emissions. It’s a small decision that makes a big difference over time.
Remember: it’s not about picking the most expensive gasoline—it’s about picking the right one.
Frequently Asked Questions
Can I Mix Regular and Premium Gas?
Yes, if you do it once, it won’t harm your car. But try to use the recommended octane regularly.
Will Premium Gas Clean My Engine?
Not really. It doesn’t contain special cleaning agents that regular gas lacks. Instead, look for “Top Tier” gasoline brands.
What If My Car Knocks With Regular Gas?
If your engine knocks when using regular gas, check your manual. If your car recommends mid-grade or premium, try using that instead.