Gasoline Myths and Facts | 4 Things All Subaru Owners Need to Know About Their Fuel Options

Things to Know About Fuel Types - Service Information at Carlsen Subaru

Nowadays, pulling up to the pump means choosing from all sorts of different available fuels! From regular, mid-grade and premium gas to diesel fuel and new ethanol blends, it can be confusing to pick out the best fuel for your car. On this page, the maintenance team at Carlsen Subaru have compiled some things every Subaru driver should know about the various fuels available for your vehicle. Knowing which fuels are safe to put in your car and which to avoid can help you make the best choice at the pump, so you save money and get all the performance you can out of your car.

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4. What is E85 Gas?

"Ethanol" is a plant-based fuel that's similar to gasoline, and can even be blended with gasoline to create a more sustainable, environmentally friendly source of fuel for cars. The number 85 sounds awfully similar to the 87, 89 and 91 octane numbers that tend to correspond to the regular, mid-grade and premium fuels available at major gas stations -- but it has nothing to do with octane rating. Actually, the name E85 refers to the percentage of ethanol that makes up the fuel: 85%. As little as 15% of E85 is made up of actual gasoline.

Thanks to renewable sources and government subsidy, E85 fuel is typically cheaper than regular gasoline -- but ethanol has less chemical energy than gasoline, so you'll get worse gas mileage. And since only FlexFuel vehicles are designed to run properly on E85, most drivers will simply ignore the E85 pump. Accidently put E85 in your regular car? Don't worry -- the check engine light may turn on, but once you top off the tank with regular gas and run the whole tank through the system, the check engine light should turn itself off with no ill effects.

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3. What is E15 Gas?

Those of you playing along at home might be able to figure this one out yourself. Sometimes found in a blue-colored pump, E15 gasoline is 15% ethanol. The difference between E15 and E85? E15 is often a bit more expensive, but still cheaper than regular unleaded. It can also be safely put in ordinary gasoline cars! In fact, most gas marked regular unleaded in America today is already up to 10% ethanol. To keep a few extra bucks in your pocket without worrying about damage to your car, you can safely choose to fill up with E15 gas in virtually every gas-burning car manufactured after 2001. This also applies to other available ethanol blends like E25 and E30.

2. What Happens if I Put Diesel in my Gas-Burning Engine?

Now this one is an actual problem. See, gas-burning engines can't combust diesel. So, once the remaining gasoline in the fuel tank and the fuel lines is used up, and diesel makes its way to the engine, it'll quickly stall and completely die altogether. You'll need to visit a professional to have the gas tank taken off the car and emptied, and -- if diesel fuel actually made it to the engine -- you'll have to have the fuel lines, fuel injectors and more professionally cleaned. This can be a costly procedure, so do your best to avoid this mistake!

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1. Does Putting Premium Fuel in my Engine Improve Performance or Longevity?

Many car owners still like to "treat" their engine to a pricey tank of premium gasoline from time to time, even though their car only requires regular unleaded. The thinking seems to be that giving it better gas occasionally helps keep the engine cleaner, longer -- but it really has very little effect. Some high-performance engines benefit from high-octane premium fuel, but the regular engines found in ordinary commuter cars will see no benefit from premium gas. If your car calls for premium gas for maximum horsepower, you can add it from time to time for a minor performance boost, but regular cars should just keep using regular fuel.

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  1. Carlsen Subaru

    480 Veterans Blvd
    Redwood City, CA 94063

    • Sales: (888) 520-5916

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Carlsen Subaru

480 Veterans Blvd
Directions Redwood City, CA 94063

  • Sales: 650-365-6390
  • Service : 650-365-6390
  • Parts: 650-365-6390

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