One of the most common questions vehicle owners face is: “What type of gas should I put in my car?” Whether you’re driving off the Tillema Auto lot in something nearly new or keeping your faithful ride running for years, choosing the right fuel is crucial for performance, efficiency, and the lifespan of your engine. Here’s how you can decide what’s best for your vehicle.

Check Your Owner’s Manual—It’s Essential

The most authoritative source for what type of fuel your car needs is the owner’s manual. Every manufacturer provides detailed fuel requirements for each model, often specifying the minimum octane rating and sometimes warning about additives or certain ethanol blends.

Always start here. Following the manual ensures you don’t void warranties or cause premature engine problems.

If you’ve bought a used car and don’t have the original manual, you can often find a PDF version online from the manufacturer, or ask a technician at Tillema Auto to help you access this information.

Understanding Octane Ratings

At any gas station, you’ll see several types of gasoline, typically listed by octane rating:

• Regular (87)
• Midgrade (89)
• Premium (91-93)

The octane rating tells you how resistant the fuel is to “knocking” or “pinging”—that’s when the air-fuel mixture in your cylinders detonates prematurely. Knock can reduce performance and, over time, harm your engine.

High-performance engines require higher-octane fuels because they compress the fuel mixture more, demanding greater knock resistance.

Who Really Needs Premium?

Not everyone needs to pay extra for premium gas. You only need premium (higher octane) if:

• Your engine is high-compression or turbocharged/supercharged.
• Your owner’s manual specifies premium as required, not just recommended.
• You notice engine knock or performance issues with lower-octane fuel.

If your vehicle’s manufacturer recommends but does not require premium, you can usually use regular gas safely. However, you may see slight reductions in horsepower or fuel economy.

What If I Use Regular Gasoline?

The majority of cars on the road today are engineered to run perfectly well on regular 87-octane gasoline.

Using a higher-octane product in a vehicle designed for regular won’t give you more power, cleaner emissions, or better mileage—it simply increases your fuel bill. The only time to deviate from this is if you experience knocking. If that happens, step up one octane rating and see if it resolves.

Flex-Fuel and Alternative Fuels

If you drive a Flex-Fuel Vehicle (FFV), your car is built to handle gasoline blends with higher levels of ethanol, such as E85 (up to 85% ethanol). Never use E85 unless your vehicle is labeled for it—using alternative fuels in a non-compatible engine can cause serious damage and void your warranty. Always check the gas cap or owner’s manual for clear labels.

Diesel vs. Gasoline: Never Mix Them Up

Diesel engines require diesel fuel. Accidentally using the wrong fuel type can result in expensive repairs. If a mistake happens, do not start the engine—have your car towed to a mechanic immediately.

Is “Top Tier” Gas Worth It?

Many automakers recommend using gasoline from “Top Tier” stations. These fuels contain extra detergents that help keep your engine clean and reduce deposit build-up inside your fuel system. While it’s not mandatory for most cars, using quality gas is a good way to preserve your engine’s health over the long haul.

Special Considerations: Climate, Driving Style, and Additives

Occasionally, factors like high elevations or extreme heat can influence fuel performance. Cars in higher altitudes may tolerate lower octane ratings due to thinner air, but always check your manual before making changes. Additionally, avoid aftermarket fuel additives unless specifically recommended—modern fuels already contain the necessary cleaning agents for most engines.

The Tillema Auto Recommendation for Choosing the Right Type of Gas

• Always refer to your owner’s manual for requirements.
• Only use premium if your car requires or strongly recommends it.
• Regular gas is ideal for most vehicles.
• If in doubt, consult a qualified technician at Tillema Auto—we’re happy to look up your car’s specs, answer your questions, and help you fuel with confidence.

At Tillema Auto, we’re committed to not only finding you a reliable vehicle, but helping you to keep your vehicle running at its best. We provide transparent advice, because at Tillema Auto, our goal is to treat you like family.

The right fuel can extend your engine’s life, boost efficiency, and ensure safe, reliable transportation.

Whether you have questions about the right type of gas, need an oil change, or need assistance with bigger service repairs, our qualified, honest technicians are here to help.

Stop by or give us a call at 616-878-5991.