Gasoline - Things You Should Know

 

Diesel

Regular

Midgrade

Premium

Octane Level

15-25

87

89

91-93

 

Octane Level – the higher the octane level, the more compression the fuel can withstand before detonating.  This means that higher octane levels of gas burn cleaner and leave less residue in your engine. 

Check your owner’s manual for the octane level best suited for your car.  Generally, your vehicle will not benefit from using a higher octane level than recommended for your car.  However, if you do hear knocking or pinging in your engine, then a higher level of octane may help alleviate that issue.  Do not always assume premium means better, your owner’s manual is the best resource for the type of gasoline your car is engineered to use.

Knocking – occurs when part of the fuel-air mixture in one or more of your car’s cylinders ignites spontaneously due to compression, independent of combustion from a spark plug.  Knocking is not a controlled burn, but more of an explosion that can be detrimental to your engine.

Ethanol – The Renewable Fuel Standard is a Federal Program which requires that transportation fuel sold in the USA contain a minimum volume of “renewable fuels” which is why most fuel stations have a label on the pump (typically E10 label) indicating that up to 10% of the fuel is ethanol.   Ethanol burns about 33% less efficiently than pure gasoline so using E10 may result in up to a 3.3% decrease in vehicle mileage per gallon.  It is still possible to purchase “pure” gasoline, without Ethanol, and pure gasoline is typically recommended for small engines, such as lawn mowers, etc as it burns cleaner and is less likely to collect moisture condensation when left to the elements over longer periods of time.

Diesel - gasoline has a much lower octane rating and should only be used in diesel engines as this type of gasoline does not ignite/burn like regular gasoline and the ignition system to ignite the fuel is very different.  It is generally used for large trucks like eighteen-wheelers.  A diesel engine does provide more torque and power, which is why it is used in large trucks.  Diesel engines, when working correctly, can provide higher gas mileage than similar gasoline engines.   That being said they have less high-speed performance and work better with heavy loads and slow tows.

Don't be intimidated by an auto service technician that is "trying to SELL you a service". 

Prepare and educate yourself to have an informed discussion at the Auto Service Shop.

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