What do the number 87, 89, and 93 mean when talking about gas?

Question

What do the number 87, 89, and 93 mean when talking about gas?

Answer 1

Octane level of the gas, AKA Quality Level.

87 Octane is Regular Gas (no ethanol)

89 Octane has 10% ethanol mixed in.

91 Octane is Premium (most expensive but best quality)

Answer 2

Octane rating, basically a higher number means the fuel takes more energy to get it to ignite.

Answer 3

They are the octane rating of the fuel, the lower the number the lower percentage octane is in the fuel.

Most vehicles on the road today call for the regular, or least expensive grade.

Answer 4

related to the octane level.

they are the measure of the autoignition resistance of gasoline and other fuels used in spark-ignition internal combustion engines. It is a measure of anti-detonation of a gasoline or fuel.

Octane number is the number which gives the percentage, by volume, of iso-octane in a mixture of iso-octane and normal heptane, that would have the same anti-knocking capacity as the fuel which is under consideration. For example, gasoline with the same knocking characteristics as a mixture of 90% iso-octane and 10% heptane would have an octane rating of 90. [1]

Answer 5

They are the octane number.  Octane rating is a measure of the resistance of gasoline and other fuels to autoignition in spark-ignition internal combustion engines.

All that means is that a high octane has a lower tendency to autoignite