Do I Need A Higher Octane In My Gas Tank
60As we begin to fuel up this summer for vacation, we assuredly notice higher gas prices. The higher the octane in our fuel (87, 92, 94, etc), the higher the price.
Do we really need a higher octane for our cars and what do those numbers on the gas pumps mean?
Octane is a chemical compound that has eight carbon atoms. That is why it’s called octane – it’s the same reason the eight-armed marine creature is called an octopus. The octane number you see on gas pumps is a measure of how much the gasoline can be compressed before it spontaneously ignites. It is supposed to ignite only from the spark from a spark plug. If fuel ignites prematurely, it causes “knocking” or “pinging.”
Fuel with an octane rating of 87 is comprised of 87 percent octane and 13 percent of one or more other hydrocarbons. A higher octane rating means the fuel can withstand greater compression, but that doesn’t mean that you should use it in your vehicle.
Your engine is designed to operate at the octane rating prescribed in your owner’s manual. That specific fuel will yield the optimum performance for your vehicle. If you use gasoline with an octane rating lower than the manufacturer calls for, it will cause knocking and may damage the engine. If you use gasoline with a higher octane rating, you are spending more money than necessary. Putting 92 octane fuel in a vehicle designed for 87 octane will not boost performance.
Next time you hit the gas pump and feel a pinch in your wallet, go for the fuel prescribed for your vehicle.
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Rusty says:
6 months ago
"Fuel with an octane rating of 87 is comprised of 87 percent octane and 13 percent of one or more other hydrocarbons."
This sentence is completely incorrect... Automotive fuel is comprised of 50+ hydrocarbons and a few other trace compounds.
The octane number you see on a fuel pump (in the US) is an average of motor octane number (MON) and research octane number (RON), commonly abbreviated as (R+M)/2.
To determine the motor octane number of a fuel, it is run through an engine, and the power settings are changed until detonation, or "knocking," occurs. A second engine is also run, with a varying mixture of iso-octane (an isomer of octane) and n-heptane. Iso-octane, by definition, has a motor octane number of 100. N-heptane, by definition, has a motor octane number of 0. The percentages of the two reference components are varied until the detonation characteristics match that of the original fuel being tested. Therefore, an 87 MON fuel has the same detonation characteristics of a fuel comprised of 87% iso-octane and 13% n-heptane. Obviously this test only works up to 100 MON, meaning it isn't valid for any fuel/chemical (e.g. some aviation fuel) that has a MON rating of >100.
Research octane number is determined by a different, more complicated test.
Please, do some double-checking on your facts before you post something like this online...
- Rusty, your friendly neighborhood fuels researcher