San Antonio Auto Repair

When you are at the fuel pump you will be faced with anywhere from 3 to 5 options of fuel types. The most common options you will see is regular, midgrade, premium, and diesel. Depending on the gas station and where you live you may also see an option for E85. Based on the vehicle you drive you may be able to use more than one of these options, however, some vehicles may limit you to only one option.

There are typically 3 grades of gasoline sold at the gas station. These different grades are based on the rating of octane in the gasoline. Generally, regular grade gas has a rating of 87, midgrade gas has a rating of 88-90, and premium grade gas has a rating of 91-94. So what does the octane rating mean? According to the U.S. Department of Energy, “Octane rating is the measure of a fuel's ability to resist "knocking" or "pinging" during combustion, caused by the air/fuel mixture detonating prematurely in the engine.” The higher the octane the more resistant it is to this pre-ignition. Therefore, if your car's engine has a higher compression ratio or uses a super or turbocharger you may require premium grade fuel. In order to determine the best grade of gasoline for your car, you should check your vehicle owner's manual. If it says that premium gas is required than you should only pump premium gas. However, if it says premium gas is recommended then you have more flexibility at the pump.

If you drive a flex-fuel vehicle or a car that is E85 capable than you have an additional option at the gas pump. E85 is a mixture of 15% gasoline and 85% ethanol and it's typically cheaper than regular gasoline. However, it is estimated that the fuel economy will be about 25% lower when using E85. It is important to remember you can only use E85 if your car is labeled E85 capable. This is usually indicated on your fuel cap, but you can also check your owner's manual for more details on the recommended or required fuel type.

If your car or truck has a diesel engine than your vehicle runs exclusively on diesel fuel. This is typically the green pump at the gas station. It is important that you do not attempt to fuel your vehicle with regular gasoline because your vehicle will NOT run and it will cause damage to your engine. This damage can be extensive and costly to repair.

Knowing the recommended and required fuel for your vehicle is very important factor in your car’s performance and fuel economy. Check your owner’s manual to ensure you are using the correct fuel grade for your vehicle. Are you noticing any recent drops in fuel economy or performance issues? This could be an indication that something is malfunctioning. Give Eurasian Auto Repair a call to have your entire fuel system inspected!

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