All About Gasoline

April 13th, 2018 by
Filling up your car’s gas tank is cheaper than it was just a few years ago. With Americans taking advantage of this reprieve from the once-staggering price for a fill-up, we’d like to answer a few questions that we get here in our Auto Repair Center about gasoline.

1. Is there a difference between known-brand and generic-brand gasoline?

Your local “stop-and-go” food mart often charges less per gallon, making them an attractive alternative to the big name gas stations. These independent station owners have no allegiance to a large company and are able to purchase cheaper, unbranded gasoline from a fuel distributor. The distributor has access to several different oil companies, and because they are not bound by an exclusive contract to a brand name, they choose the lowest price and pass that on to the smaller stations.
For budget-conscious drivers, studies show that the unbranded, “generic” gasoline works fine in your car. You don’t need to pay extra for the “special fuel additives” that big oil companies claim help your engine.

2. What is the difference between diesel and regular unleaded gasoline?

Gasoline and diesel are both fuels generated from crude oil.  When a barrel of oil is refined and separated, four general fuels are made.  Gasoline is the most refined and lightest weight (excluded from conversation is mixing ethanol/alcohol or other additives).  The next most refined is jet fuel, followed by diesel, then the “heavy” fuel that is used to power stuff like cruise ships and trains.
Gasoline (otherwise known as petrol everywhere else) is very light weight and highly flammable.  The combustion of gas plays to those traits.  In gasoline motors, a very fine mist of gasoline is sprayed into the cylinder where it immediately evaporates, and then is lit on fire by a spark plug, thus creating force to continue the stroke of the piston.
In a diesel motor, the fuel is heavy or dense; making the mixture is far more stable and less flammable.  In turn, the per litre potential of power is less, but more efficient because diesels power is derived from fuel rate rather than air flow.  The engine itself does not rely on spark to ignite the fuel, rather it is a true combustion generated by compression.

3. What is octane, and how do I know which octane level is right for my car?

The octane rating of gasoline refers to the performance, or compression ratio, of your car’s engine. It tells you how much the air-fuel mixture can be compressed before it will spontaneously ignite. A higher octane number allows the fuel to tolerate more compression before igniting.
Although many people think that using a high-octane gasoline gives their engine more power, better performance, and keeps it cleaner, this is not true. Octane ratings measure a gasoline’s ability to resist the engine knocking we mentioned above. Most cars do fine on regular octane, with the exception of certain luxury and sports cars that need mid-grade or premium gasoline to prevent knocking. Consult your owner’s manual, and then listen to your engine. If you don’t hear any rattling, you’re choosing the right grade of gasoline.

4. What is ethanol, and do I really get better gas mileage buying ethanol-free?

Ethanol fuel is ethyl alcohol, the same alcohol found in alcoholic beverages. Also called “bioethanol,” this renewable energy source is made by fermenting the sugars and starches found in sugarcane, corn, potatoes, grains, and some fruits. Ethanol is blended with gasoline to make a more sustainable and environmentally friendly fuel that produces cleaner emissions.
Most of the gasoline sold in the US today contains approximately 10 percent ethanol in order to meet the requirements of the 1990 Clean Air Act and the Renewable Fuel Standard established in 2007. It’s very hard to find ethanol-free gasoline. All cars are certified to run on 10 percent ethanol, or “E10” gasoline.
Don’t worry too much about your mileage using E10 gas. Your fuel economy decreases by about 3 percent, or 1 mpg for a car rated at 30 mpg combined city/highway.

5. My car is consuming fuel faster than normal. Could that have something to do with the gas I bought?

If your car begins to eat gas faster than usual, it is most likely related to damaged parts or your driving habits. Under-inflated tires, worn out spark plugs and a clogged air filter can all cause your car to burn through gas faster. Dragging brakes and fuel and vacuum leaks also lower your miles per gallon. Fast or aggressive driving and excessive idling also reduce fuel economy.
To ensure that your sudden increase in fuel consumption is not related to a worn out part that could lead to more extensive damage down the road, use our easy scheduling tool to book a check-up for your vehicle. Our highly-qualified service department technicians get you in an out fast, and the comfortable lounge at Safford Chrysler Jeep Dodge of Warrenton offers free Wi-Fi so you can even work while you wait.
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