Shop Talk Logo

What You Need to Know About Gas for Your Car

When it’s time to fill up at the pump, you may have wondered what the difference is in types of fuel for cars. From diesel to high and low octanes, it can be a tricky choice for any driver. Gas is just gas, right? Your car is just happy to have the fuel it needs to keep moving, right? Wrong. Learn which kinds of gas are out there, their differences, and how to choose the right one for your car. Here’s what you need to know:

Types of Fuels

Gas or fuel is made from crude oil and is highly combustible and is the fuel most vehicles use to power the engine. There are several different types of fuel including:

  • Diesel
  • Regular/Unleaded (87)
  • Mid-grade/Unleaded (89)
  • Premium/Unleaded (91) or (93)

Diesel is made from petroleum crude oil and has larger hydrocarbon molecules and more carbon atoms than regular gasoline. Diesel engines differ from gas combustion engines in when and how fuel burns.

Diesel engines don’t have as much horsepower as gas engines but produce a lot more torque which assists in pulling power.

What does the number mean?

The number next to the type of gasoline refers to the amount of Octane it contains.  Octane is a colorless, flammable hydrocarbon obtained in petroleum refining used to determine the explosiveness of gasoline and is the measure of how much compression a fuel can tolerate before igniting.

When the fuel ignites prematurely, known as pre-ignition, this explosion can cause damage to the engine.

That knocking sound you hear may be caused by pre-ignition. The higher the octane rating, the less likely this will occur.

Premium gasoline (90 or higher) contains a higher amount of varying detergents and additives that help engines run cleaner and more efficiently. Premium fuel helps to emit fewer pollutants into the atmosphere.

Which Fuel is Right for Your Vehicle?

gas tankHigher octane gasoline has no more energy potential than lower octane gasoline. Using a higher-octane fuel on vehicles that do not require it will not lead to better gas mileage or burn efficiency. Most gas stations will offer three different levels of octane. Same fueling stations may call their mid-grade “plus” or “special” and their premium “super.” If you’re unsure of the octane based on the description, look for the indicating numbers to help aid your selection.

You will find information on which fuel to use in your car in your owner’s manual or on the inside area of the fuel door cover. If your vehicle requires premium fuel, you must use premium as certain vehicle fuel systems and engine compression are designed to work best with a higher-octane gas. Some high-compression engines require premium fuel to prevent engine knocking. Higher compression engines generally produce more power, thus the need for higher octane fuel.

Burning regular fuel in an engine designed for premium fuel on a long-term basis or under heavy loads can cause engine knocking and damage to the engine. Even though the vehicle has a knock sensor that adjusts the spark timing, and you do not hear knocking, you may still be damaging your engine.

If you use a lower octane than advised for your vehicle, you can expect:

  • Severely reduced performance because the engine will attempt to adapt to the lower octane gasoline.
  • A decrease in fuel economy.
  • A possible void to your vehicle warranty.
  • Permanent damage to pistons, valves, or spark plugs.

Use only the fuel recommended by your vehicle manufacturer.

Quality Counts

Top tier gasoline has two to three times the required amounts of detergents and cleaning agents required by the Environmental Protection Agency (EPA), helping your fuel injectors remain clean, no matter what grade of fuel you purchase. Top tier gasoline if produced by major-brand name fuels.

If you’re looking to save money at the pump, spend your fuel dollars on top tier gasoline as opposed to higher octane fuels if not required. Your vehicle from the fuel tank to the engine will benefit from higher quality fuels.