what is octane?

The higher the octane the higher the temperature that is required to support complete combustion of gases.
The compression ratio of the engine determines what octane rating you should use. The lower the compression ratio the lower octane you should use.

Consult your vehicle's owners manual to find out what type of octane rating is recommended for your engine. Using higher octane then recommended will not save you any gas mileage or reduce the amount of exhaust emissions. It will just be a waste of money.

its an additive that allows gasoline to burn at 160 ft. per second instead of exploding & damaging your engine a higher compression ratio requires a higher octane rating to resist detonation of the air fuel mixture. when the government mandated the removal of tetraethyl lead (an octane modifier) from gasoline it lowered the octane rating from 92 to 87. all cars made after 1971 had to run on 87 octane. to do this the car companys reduced compression from 91/2 or 10 to 1 down to 8 1/2 to 1 thus reducing h.p. & increasing fuel consumption as much as 20% for the same engine.

Octane is a measurement of, "the resistance to burn."

How you know what brand of gasoline is? pumped to tank in vehicle. High octane is better; so it costs more... I suggest you only get what's needed. Why pay more then have 2? :C 1 reason diesel is costly due to fact it's brand associated with work vehicle's... I could ramble on T.O.'s, but it's has been many moons since I was POL. A gas station might know or if near a military base with fuels in it
( of course) ask a fuel's person for access to the Tech order or a T.O. for info. it will post. We call gas Mogas

Octane itself is a colorless liquid, one of the components of gasoline. Octane number is a measure of one of the combustion properties of gasoline. The higher the number, the greater the delay in its ignition in an engine cylinder after the spark plug fires, so a higher compression ratio is needed for it to work properly. "Regular" gasoline has an octane number of about 87.5, and "Premium" gasoline has an octane number of about 95. There are "mid-grades" in between those, ranging from about 90 to about 93.

The correct fuel to use in your car's engine is determined by the manufacturer when the car's engine is designed. The more the gasoline-air mix is compressed in the cylinders, the higher the octane number of gasoline needed, and the more power the engine develops. Using a lower octane number gasoline than recommended will make the engine run roughly and not give as much power. Using a higher octane number gasoline than recommended will not provide any more power and is a waste of money.

In chemistry, octane refers to an 8 hydrocarbon chain, C8H18.
In cars, today, it refers t a rating for knock control, 100 is a performance rating. Octane rating is how much it can be compressed before igniting from compression. There also is an oxygenating factor. It used to be easier to say an octane rating told how much of the gasoline was octane or C8H18. Now it is more complicated.

Octane is not a "thing" It's a way to measure a fuel's ability to keep internal combustion temperatures lower to prevent pre-ignition (death rattle) Octane ratings are not consistant as different agencies use different methods of to come to a particular rating. Lower octane rated fuels tend to burn hotter in an engine than those with higher ratings. Higher rated fuels allow higher compression and more ignition timing without detonaion that kills pistons.