FUEL: Different Types of Fuels and If You Can Use Them

Fuel

Different Types of Fuels and If You Can Use Them

Types of Fuel

Gasoline

Octane Ratings

The octane rating tells you how sensitive the fuel is to compression. Unleaded gasoline typically has octane ratings of 87 (regular), 88–90 (midgrade), and 91–94 (premium). Gasoline with an octane rating of 85 is available in some high-elevation areas of the U.S.(1).

Your vehicle’s octane rating is determined by the manufacturer and it should be listed either on the gas flap or in your owner’s manual. Vehicles with a high compression rating require a higher octane fuel and the same goes for supercharged or turbocharged vehicles. High octane fuel in these vehicles will improve performance and fuel economy.

The sale of 85 octane fuel was originally allowed in high-elevation regions—where the barometric pressure is lower—because it was cheaper and because most carbureted engines tolerated it fairly well. This is not true for modern gasoline engines. So, unless you have an older vehicle with a carbureted engine, you should use the manufacturer-recommended fuel for your vehicle, even where 85 octane fuel is available (1).

Ethanol

Ethanol is a renewable, domestically produced alcohol fuel made from plant material, such as corn, sugar cane, or grasses. Using ethanol can reduce oil dependence and greenhouse gas (GHG) emissions. Most of the gasoline sold in the U.S. contains up to 10% ethanol—the amount varies by region. All automakers approve blends up to E10 in their gasoline vehicles. The number after the "E" indicates the percentage of ethanol by volume. (2).

 A vehicle's owner’s manual may indicate the maximum ethanol content recommended for it by the automaker. Ethanol contains about one-third less energy than gasoline. So, vehicles will typically go 3% to 4% fewer miles per gallon on E10 and 4% to 5% fewer on E15 than on 100% gasoline.

As of 2011, EPA began allowing the use of E15 in model year 2001 and newer gasoline vehicles. E15 pumps must be labeled as such. E15 should only be used in flex-fuel vehicles and 2001 or newer vehicles. However, It is best follow the owner’s manual/automaker. It should not be used in other vehicles, boats, or gasoline-powered equipment because it can cause damage and is prohibited by Federal law.

E85, also called flex fuel, is an ethanol-gasoline blend containing 51% to 83% ethanol, depending on geography and season. Summer blends tend to have more ethanol while winter blends have less. E85 can be used in Flex-Fuel Vehicles, which are specially designed to run on gasoline, E85, or any mixture of the two.

Ethanol-Free gas is pure gasoline. It is not mixed with any plant based Ethanol. Sometimes called “Marine Fuel”, it is usually used in boats, Jet Skis (and other PWC), lawnmowers, and other gas powered equipment. This is because ethanol-free gasoline takes longer to break down.

Diesel

Diesel fuel can only be used with a diesel engine. Diesel engines are more fuel-efficient and have more low-end torque than similar-sized gasoline engines, and diesel fuel contains roughly 10% to 15% more energy than gasoline. So, diesel vehicles can often go about 20% to 35% farther on a gallon of fuel than their gasoline counterparts (3).

A gasoline engine takes a mixture of gas and air, compresses it, and ignites the mixture with a spark. However, a diesel engine takes air, compresses it, and injects high pressure fuel into the compressed air. The heat of the compressed air ignites the fuel spontaneously (4). Since diesel fuel needs to be injected at high pressure, diesel vehicles use high pressure mechanical fuel pumps to pressurize the fuel.

Diesel fuel also has better lubrication properties than Gasoline, and those properties are used to lubricate the high pressure fuel pump and injectors in a diesel fuel system.

Bio-Diesel

Biodiesel can be used in its pure form (B100) or blended with petroleum diesel. Common blends include B2 (2% biodiesel), B5, and B20.

Most automakers approve blends up to B5. Some approve blends up to B20. Check with your owner’s manual or automaker to determine the right blend for your vehicle. Using the wrong blend could damage your engine and/or void the manufacturer's warranty.

Note: Never fuel your car with grease or vegetable oil that has not been converted to biodiesel. It will damage your engine (5).

What happens if I use the wrong fuel?

When a lower octane rating than required is used:

Using a lower octane fuel than required can cause the engine to run poorly and can damage the engine and emissions control system over time. It may also void your warranty. In older vehicles, the engine can make an audible "knocking" or "pinging" sound. Many newer vehicles can adjust the spark timing to reduce knock, but engine power and fuel economy will still suffer (1).

When a higher octane rating than required is used:

For most vehicles, higher octane fuel may improve performance and gas mileage and reduce carbon dioxide (CO2) emissions by a few percent during severe duty operation, such as towing a trailer or carrying heavy loads, especially in hot weather. However, under normal driving conditions, you may get little to no benefit and is not worth the increased cost (1).

When fuel with a higher Ethanol percentage (such as E85) than required is used:

If your vehicle is not equipped to run on flex fuel, then you may notice reduced gas mileage and performance and your Check Engine Light will most likely come on. It should not cause any long-term damage to your engine if you misfuel once. Repeated use will cause damage to engine components and the catalytic converter. The best course of action would be to continually top it off with regular gas until it has worked its way out of the system (6).

When Ethanol-free gasoline is used:

There should be no damage caused to your vehicle. If anything, it may help your vehicle run better. It may improve your gas mileage and cause less harm to your engine than normal E10 gasoline. However, it is does cost more than normal gas and is also more harmful to the environment.

When diesel is put in a gas vehicle:

Stop driving immediately - park and turn the engine off to limit damage. The vehicle will need to be towed to a repair shop. Gas engines cannot combust diesel fuel so the vehicle will eventually shut down. Since diesel fuel is thicker and denser than gasoline, it is harder for your fuel pump to move it through the system and will clog up the injectors. It may not ruin your engine, but could definitely damage parts of your fuel system (6). The entire fuel system will need to be drained of the diesel fuel and cleaned.

When gas is put in a diesel vehicle:

Do not start your engine. The vehicle will need to be towed to a repair shop. As long as the engine is not turned on, the gas will not contaminate the internal components. The fuel tank and fuel system will need to be drained and flushed out.

Running the vehicle will cause catastrophic damage to your engine. Since diesel and gas have different combustion properties, the gas will detonate much earlier in a diesel engine. This will cause you to have misfires and knocking that will damage your engine. Since gasoline does not have the required lubrication, metal components (in the fuel system) will be rubbing against each other and cause permanent damage. Along with draining/cleaning the fuel system, your engine and fuel system may require repair, rebuilding, or even replacement.

Resources:

https://www.fueleconomy.gov/feg/octane.shtml

https://www.fueleconomy.gov/feg/ethanol.shtml

https://www.fueleconomy.gov/feg/di_diesels.shtml

https://www.ezoil.com/resources-diesel-diesel-engine-basics

https://www.fueleconomy.gov/feg/biodiesel.shtml

https://www.autoguide.com/auto-news/2016/07/what-happens-if-you-put-the-wrong-fuel-in-your-car-.html